Before looking at other ways to revise your story, this bit is about knowing when you're finished. I'm sure we all know the tinkers who take the manuscript and tinker with the story forever. I once had a friend who revised the same first chapter for five years. She never finished the book and I don't think she's still writing. I had another friend who only looked to make sure the spelling and grammar were right in her mss. She revised no further and just sent the mss out to editors. Unfortunately most of the time, the stories came back with that "This story doesn't suit our needs at the moment." So how do you know when you're finished and what do you do.
For me the moment comes when I thing If I look at this material one more time I'm going to throw up. It's time to send it off.
Now after the rough draft, I've done the Plot draft, the Setting Draft, the Character draft and the language draft. By this time I am thoroughly sick of the story.
There's another tell in my life. At night, I start dreaming of the next story and suddenly the plot begins to gel. Time to get rid of the old and on to the new.
There are ways to do this. One is to submit to a publisher. If you have one who will look at all you write, you're in luck. Then there are friends who can read the story andhelp you decide if it's done. Now that can be a problem and you must remember friends should only be reading to see if they enjoy the story. There are also other kind of readers for your story. Often they give great feedback and then occasionally, they want to rewrite your book so that it becomes not yours but theirs. This can happen with editors, too.
But after you write The End, put the story aside for a few days or weeks and then look at it again. Then send it on its way. Of course after the book is published, you can think of other ways you could have made it better. Too late. Save that knowledge for your next.