Ya I would say bump the humidity up. Ya mites thrive better in higher humidity but why make the a bad shed add to the problem. Also, if your diligent and can catch the snake actually shedding, take her out and clean entire cage throughly. When the snake sheds all the mites come off with the shed so the sooner the better. (NOT A 100% EFFECTIVE STILL NEE THE PAM) but that will help the problem also.
Also any hides that arent plastic bake at 250 for 30 min to an hour along w water dishes... Mites lay eggs and they get in the crevices. The heat will kill those.