At Lyme, it says the fresh air and climate cause Anne to have a second bloom, but I would argue that she begins to bloom again in the presence of Captain Wentworth. His small kindnesses to her at Upper cross (taking her nephew off her back, asking his sister to give her a ride when she is tired) show his continued affection for Anne and I think that is why she blooms. Just knowing that he still cares about her, if only because of former attachment, is enough to warm her heart.
Like a flower that wilts when it needs water and sunlight, she finally gets some Fredrick-love, however indirectly, and begins to perk up. He is her sun and she turns to drink in his warmth.
What do you think?