I just got out of a DSG meeting with the Future Doctor Anderson. We were discussing how we both dread doing research on a chapter now that we’re in the dissertation-revision stage. It’s discouraging to “go back” to reading after one’s been writing a lot.
Looking back on my most recent chapter revision, though, I had to admit that I did almost no unnecessary research for that draft. Unlike the first draft, where there are understandably a lot of dead ends, and one spends time writing many pages that are later cut–in a late revision, one spots relevant material almost immediately. Research is so much easier once there’s a draft or two already completed.
I enjoyed researching for my chapters, but the process took a long time. The research I have to do to revise my next chapter is touch-up research: just a few little spots need filling in. I don’t have to scrape off all the old paint and start over with primer.
Becoming Doctor Jones 
So glad to hear you only have touch-up research to do on the next chapter!
What you wrote reminds me of something a professor of mine said in college. Good research is a circle. You start at the top of the circle with a question. If it’s a question worth asking, you gather information, synthesize it, and come back to the top of the circle with even more questions!!!! And the cycle continues. But if all of your questions were completely answered, it probably wasn’t a very interesting question. So, I know it’s frustrating to revise, but… maybe you can think of it as a sign that you’re working with a good question ;)