Without a doubt, rewriting is probably the hardest part of editing. You've got a scene, but maybe it didn't work for your beta readers. Maybe your computer spazzed and you lost a bunch of work. For whatever reason, at some point, you'll have to rewrite. It's inevitable. So, you can either look at as a chore or an exercise in being awesome. Recently, Jack unearthed his college thesis. It was a study of the immrama of days past. Something, something boats, ocean voyage, rite of passage. I should know more about the genre, he spent plenty of time telling me all of the ins and outs, but I'm a bad friend.
Anyway, he found it and realized he still loved the story he was telling. So, he's going through it, salvaging what he can and ditching the rest. College Jack was not nearly as good a writer as present Jack. What this amounts to is a lot of rewriting. And rewriting. And rewriting. And rewriting. Basically, none of his prose is usable. He had to cut four entire characters and rework their pertinent qualities into other characters. Every single time he's presented it to our group, we've asked him to completely redo something. And he's done it. Fantastically so. Each new iteration is better than the last. Shannon ran into the same issue with Ride the Train. There are several scenes that are nothing like they were in his original draft. And the overall story is so much better for it.
If you look for writing prompts, you'll almost certainly find some that pose the question of "what if that scene in your story had gone differently". It's easy to dismiss them. Why bother writing a scene that you won't use, right?
But just by writing it, you're using it. It's like rehearsal. It's practice.
I've done NaNoWriMo for years now. I've even actually met the goal a few times. Not a single one of the novels I've written has even turned into anything, but the characters and scenes have. I've cut and pasted them into new stories.
So, maybe go ahead and read that old trunk novel. See what parts of it you still like. Write that scene that you know isn't going in the book. Add these to your toolbox. When you need them, they'll be there. Ready to be remixed.
Edit: Just as I finished writing this, Jack realized that he'd written a character to be in two places at once. For an entire chapter. I would like to thank him for making my point so succinctly.