She was proceeding directly to her favourite walk, when the recollection of Mr. Darcy's sometimes coming there stopped her, and instead of entering the park she turned up the lane, which led her farther from the turnpike-road…he was moving that way; and fearful of its being Mr. Darcy, she was directly retreating. (Chapter 35)

In Chapter 35 Lizzy still feels Darcy is the last man in the world whom she could ever be prevailed on to marry and tries to avoid him in the park. She cannot of course and his letter shockingly reveals he is not exactly as she believed him to be and by the time she returns from the park in Chapter 36 Darcy’s letter has supplanted Col Fitzwilliam in her thoughts—she could think only of her letter and in Chapter 37 she was in a fair way of soon knowing it by heart by studying every sentence.

When she remembered the style of his address, she was still full of indignation; but when she considered how unjustly she had condemned and upbraided him, her anger was turned against herself; and his disappointed feelings became the object of compassion. His attachment excited gratitude, his general character respect; but she could not approve him; nor could she for a moment repent her refusal, or feel the slightest inclination ever to see him again. (Chapter 37)

In Chapter 37 Lizzy’s feelings about Darcy vary greatly depending on which incident she thinks of. She has respect for him and no longer believes he is dishonorable. She is able to feel compassion for his disappointed hopes, something she could not do during the proposal because she lost her initial compassion in anger at the mode of his address. Her compassion is mentioned twice after the proposal, Chapter 37— “his disappointed feelings became the object of compassion” to a more established feeling in Chapter 40— "Indeed," replied Elizabeth, "I am heartily sorry for him…” Lizzy still does not like him and cannot approve him. Darcy is a respectable but an often disagreeable man. Although she does not repent refusing Darcy she amuses herself by imagining Lady Catherine’s indignation if she had been presented as her future niece.

"This will not do," said Elizabeth; "you never will be able to make both of them good for anything. Take your choice, but you must be satisfied with only one. There is but such a quantity of merit between them; just enough to make one good sort of man; and of late it has been shifting about pretty much. For my part, I am inclined to believe it all Mr. Darcy's; but you shall do as you chuse." (Chapter 40)

I have taken “quantity of merit between them” to mean Lizzy thinks Darcy is a good respectable man although she still thinks his manners are disagreeable because the only merit I think she would apply to Wickham at this time is pleasing manners. In Chapter 41 Lizzy is shamed by her younger sister’s and mother’s lamentations caused by Mr. Bennet’s refusal to take the family to Brighton. She feels Darcy’s distain for her family’s impropriety is more justified than ever and she tells Wickham neither Darcy’s mind or manners have improved but knowing him better increased her understanding of his disposition. Now she also sees through Wickham’s manners and they fail to charm. I cannot help but think Wickham has succeeded to the honor of the last man in the world Lizzy could ever be prevailed upon to marry followed distantly by Mr. Collins—I think Darcy has redeemed himself enough at least to move down the list to the third least agreeable man of her acquaintance.

Elizabeth was distressed. She felt that she had no business at Pemberley…Elizabeth said no more -- but her mind could not acquiesce. The possibility of meeting Mr. Darcy, while viewing the place, instantly occurred. It would be dreadful! She blushed at the very idea, and thought it would be better to speak openly to her aunt than to run such a risk. But against this there were objections; and she finally resolved that it could be the last resource, if her private enquiries as to the absence of the family were unfavourably answered. (Chapter 42)

Finally, at the end of Chapter 42 Lizzy is set to visit Pemberley but only with the assurance of not meeting Darcy because she thinks it would be dreadful—I suppose dreadful as in embarrassing for both them. She wishes to avoid meeting him so much she thinks of confessing some of the events at Hunsford to Aunt Gardiner. This is to her complacency as well as his but I do think it reflects favorably on Darcy. “She felt she had no business at Pemberley” suggests to me Lizzy feels she would be wrong to impose her presence on him so I take that as some care of what his feelings would be in seeing the lady who rejected him and wrongly accused him. This is a change from her challenges he took for flirting and her expectations of affronting him as she tried to do, for example in Chapter 10, “Elizabeth, having rather expected to affront him...” I think Lizzy does not regret refusing Darcy but she does regret her treatment of him. Although she admits Darcy was right about her family’s impropriety I think his no-apologies separation of Bingley and Jane shows he values pride too much to be the friend of a man with connections to her family. She respects him, feels he is honorable but does not like him and cannot approve him. (;D) She does however, as she always has, have continued feelings of curiosity about him:

her alarms being now removed, she was at leisure to feel a great deal of curiosity to see the house herself; and when the subject was revived the next morning, and she was again applied to, could readily answer, and with a proper air of indifference, that she had not really any dislike to the scheme. -- To Pemberley, therefore, they were to go. (Chapter 42)