If you are harvesting tomorrow, I would not worry, he won't eat much, just a little bit of chlorophyll.
As my esteemed co-contributor stated, there is no need to treat the plant with anything, this would make your buds unusable to consume due to residual amounts of whatever you used still being in the plant material. After harvest, the spider mite will wander off looking for another living plant to feed on. Also as my esteemed co-contributor stated, cleaning your grow space THOROUGHLY can not be underestimated, as eggs and possibly adult spider mites could be lurking and waiting for a new food source, so cleaning before introducing any new plants are introduced, is vital.
Hope this helps,..... Organoman.