Honestly, I let it run its course. I've never had writer's block so severe that a couple days (even a couple weeks or months) off from writing didn't cure or at least temporarily alleviate it. I don't push myself to write when I don't want to unless I absolutely must for deadline reasons, and as a result I rarely get writer's block. I think it's a chicken/egg thing: not forcing myself to write when it's not working makes me less stressed about writing, which in turn makes writing come easier--and brings on the sort of ideas that can break a writer's block for me. There are a lot of ways to deal with writer's block, but that's mine.