i have to step away from it and look at it from a different angle and hopefully figure out what i'm doing wrong or right. or i'll leave and look at it the next day with new eyes.
If I get to a point where a painting isn't working, I move forward with the rest of the painting filling in areas that I have avoided or thought I would add later. Using this approach usually resolves the problem and gets me closer to a completed painting. Good luck!