Buy a handheld steamer and steam EVERYTHING daily. Pay close attention to baseboards, cracks in the bed frame, the entire mattress, and especially the creases on the mattress. Also toss all bedding, clothes, and other loose items in the dryer on high for 30+ minutes, the heat kills them.
We had them growing up and my mom used Borax in a bowl with our legs to the beds and anything else she could fit into a bowl. Wash everything in hot water and dry on the hottest setting your dryer will allow.