When you read the same after a few days, you'd feel like banging your head against the wall and giving up. It's okay to do the former, but don't ever give up! Improvise on it. Sometimes, you'll have to erase the whole thing and write from scratch. This can get on your nerve and make you go super crazy, but remember, if you give up, you'd be denying the world what might have become one of the best piece of literature.
A good writer is a great reader. Read a lot, appreciate and admire the works of fellow writers, share their work, discuss in writer forums and ultimately, give of yourself to literature.