Let the words reveal themselves
After a couple of days like this where I read and re-read my work, I decided to pick up my pad and pen and write it all down. I copied out the sections that worked and in doing so, found that when I came to the paragraphs I wanted to change, the words just revealed themselves. Whether it was the nature of writing it all down (the intention and focus) that helped me out of my trough, I have no idea. It worked though. Suddenly I could see what I needed to change and what words to use.
So if you're stuck with your writing, have a go. If it worked for me, it could work for you too.