That depends on the spray and the enviroment around the cage. It's best to clean as much as posible; the cage and it's suroundings and to continue treatment for an apropriate amount of time.
What I mean is that the cage and every thing in it should be totally cleaned at least once a week for a month or more and the mite treatment should be repeated. If the spray is safe to spray around the area of the cage then that might be helpful...check the instructions.
If there is anything the nonconformist hates worse than a conformist, it's another nonconformist who doesn't conform to the prevailing standard of nonconformity.