I'll throw in my own (sorta similar) frustration. I have a quasi-military sci fi piece that I did several years ago. I've always had a soft spot in my heart for the female protagonist---but.... I've grown as a writer so much since then that when i try to go back to expand its horizons from a 26,000 word novella to a 100,000 word novel, I get frustrated. All I do is edit, edit, edit and curse myself for my stupidity only a few years ago...
I don't know what the answer is...
- scrap and start from scratch with the same premise and same characters?
- or keep editing until it's right and then re-start the over haul?
Yes, the right answer would probably be, close your eyes and start writing the new parts, and edit only a bit at a time. I can't seem to do that!!! I really am not OCD most of the time!!!
Either of those ideas sound like a plan for your story?
If so, let me know and maybe I'll have an answer to my delimna.