here are some of the things I try to get things moving when I'm stuck rewriting the same paragraph or section again and again:
(1) read it out loud. It's really amazing how things jump out at you when you try this. Usually I end up striking out whole phrases. I'll read it out loud until it sounds right to my ear. I can even have the computer read it aloud to me, but the intonation is so funny that mostly I save this for when I'm in desperate need of a laugh.
(2) get rid of prepositional phrases. I've found that if a sentence isn't working, it's often because I've stuck too much in it. Five pounds of potatoes in a two pound bag, tra la.
(3) in an extreme case, I print a passage out, and then use a pen to cross out every adjective and adverb, along with every prepositional phrase. What's left? The bones, if there are any. Once I identify those, I can usually figure out what to put back in.
(4) I ask myself the crucial question, which is not so much what happens next but why does this happen next (and following from that) does this need to happen at all?