I have been working on revising an upper MG manuscript that actually began from something I wrote a long, long time ago. I liked the characters and theme and built around what I had. I felt pleased with the result. That was nearly a year ago. Then I read more and learned more and realized, oh! My main character isn't active enough. He needs to make more decisions and push the action more. So I made more changes. Then I read about strong beginnings and made changes based on that. I've worked and worked on this story...but in the end, I think I've decided that it's time to set it aside and begin a fresh work. I think I need to take all the things I've learned and start fresh with a brand new story.
My husband and I both came up with the same analogy independently of each other, which is both eerie and neat, and it's something Jesus talked about in the New Testament-- the folly of putting new wine in old wineskins. The idea is that the new wine will be ruined this way and instead, you need fresh containers for the new stuff. He wasn't talking about writing skills when he was talking (or actually about wine, either), but I think it works for this analogy, too.
I think everything I've learned this year is the new stuff. It needs a new place to go, a clean slate. So. Time to start fresh!