Hi Linfel –
Pest insects are often fatally traumatized from the force of the Bug Blaster and do not return. In many cases, all stages of the pest are eliminated (egg, larva and adult). For heavy infestations use the Bug Blaster every 3-5 days.
Azamax and SNS217 are two other products that we often recommend for controlling spider mites. I’ve included several links below that should help.
https://www.planetnatural.com/pest-problem-solver/houseplant-pests/spider-mite-control/
https://www.planetnatural.com/product/azamax-azadirachtin/
https://www.planetnatural.com/product/sns-217-spider-mite-control/
https://www.planetnatural.com/product/bug-blaster/
Best of luck!