I've used
Azamax with great success. It usually takes around 3 applications to really get them under control but, as Pipecarver mentioned, it's going to be hard to completely eliminate them unless you clear out the room and bleach it down as he suggested. This is why I use safety protocols whenever I enter my tent. I have a canvas jumpsuit that I used working at other grow ops that I spray down with permethrin spray before I enter the tent to kill off any hitchhikers looking for a free lunch!
Prevention is WAY easier in the long run than having to deal with an infestation. I've seen entire crops get taken down within days from spider mite infestations!
Whatever you use just make sure you coat THE ENTIRE PLANT TOP AND BOTTOM. Under leaves and branches especially since they like to hide there. Depending on the severity of the infestation I'll also do a soil drench application on the first go round to kill whatever mites and eggs are hiding in the soil.