yeah ...need to pull the plant from what ever potting media its in -
the reason for removing the potting media from plant is that spider mite eggs & larva are in that upper most level of potting media ....dump that, and you decrease the spider mite population
re-pot in about 10 to 14 days - with *clean* potting media ....
submerge rock in plain water - let soak for a few days .... rinse and they should be like new
a few ways to increase humidity is with a mister bottle filled with straight water - spray a few times a day - spider mites will hate it - your plants will love it
also use pebble trays filled with water (top off every few days)
assume all plants have at least one stage or another of spider mites ....watch closely ...need to stay on top of things, catch it early and spider mites can be eradicated ....treat only where you see them