One of the best bits of writing advice I have ever received was, when revising, to rewrite your entire manuscript, every single word. Not only are you more likely to catch and correct errors that you may have missed otherwise, but it allows you to be more ruthless when cutting down a story. I have taken this advice to heart.
Every time I'm revising or editing or restarting a story, I open up a new document and start from scratch. I'll have the original manuscript open in another document or printed out with various changes made in pen, then I'll go through and make the changes I need as I retype the entire story over again. Effective? Yes. Time-consuming? Also yes.
I have found that by saving all the previous drafts of a manuscript, it allows me to make changes without fear of losing what I've already written. If I truly need or want something I've cut, I can find it in another document.
Even when trying to find grammatical errors and typos, I've created new documents. My mother recently read Just Friends and found some errors that she pointed out to me, so I just spent the last hour creating new documents for each chapter so that I may find and correct the errors more easily. I didn't retype it all, but there are now fifteen new documents sitting in a folder on my Google Drive with fewer mistakes than in previous drafts.
Rewriting stories is difficult, though. It's one thing to know exactly what changes need to be made, but starting a story over because you lost momentum or the plot simply did not work makes things harder.
In high school, I attempted to write a dystopian novel about a world post-nuclear explosion, where a scientist went out into the world to try and determine how to make the world inhabitable again. The story was rich in background details, but the plot itself dragged on to 60,000 words without ever reaching the climax so I gave up on it. I tried returning to the story later on, starting from scratch but with the same basic premise, but that next attempt didn't go anywhere either.
The lesson from that story isn't that I failed, however. By trying to write and rewrite this novel, I learned the importance of cutting the fat from a story, as well as the fact that I prefer writing short stories over novels. Should inspiration strike, I may try writing this story again, but who knows?
I do have other rewrites planned, though. I started a rewrite/new draft of a story that I began during NaNoWriMo and have already gotten further in the plot than I had previously. Also, "Experiment", "Izoterra", and "Endeavor" (all stories intended for Interrobang) will likely require a rewrite before I can publish the collection.
The point of all this is to say that rewrites are part of the process and it's a very important aspect of editing and revisions, at least for me. Without rewrites, who knows what state my stories would be in?!
Every draft is different in some way, and even if you don't end up using it in the future, saving it is just as important as writing the next draft.