I am actually doing this right now. I wrote my debut novel over a period of about 10 years. I wrote it before I got my English degree and I wrote it before I got my Master in English. I have literally written about a million words since then. (school and pleasure) I had it edited and published as it was, but when I recently went back and re-read some of it, I realized it wasn't up to my current standard. It isn't bad, just not the way I want it and not how I remembered it, so I have spent the last week going over it and smoothing out the prose,adding some words for clarity etc. I am not changing the story at all, just improving the prose and making sure everything fits for books 2 and 3. I will send it back to editing too. However, after this overhaul, I am vowing never to return to it. I will improve it to the best of my ability and then it's just going to have to stand on its own. I have other stuff to write!