In one of my critical editions (Broadview literary) it mentions that Jane Austen wrote to her niece Fanny Knight in March 1817 (only 4 months before her death :-( ) "I have a something ready for Publication, which may perhaps appear about a twelvemonth hence."

The notes to this say:

The novel had been finished in August 1816 and Austen's silence about it for several months has led critics to speculate that, had she lived, Austen would have continued to work on the text. In fact, Austen's comments to Fanny clearly indicate that as far as she was concerned Persuasion was complete, though since no manuscripts of her published texts survive [that is in the process of being published] we do not know what kind of revisions she usually made during the production stages of her novels.