Here's one idea:
As well as treating your dogs, you need to treat your home and yard and clean clean clean. Here are some things to try.
I normally use Dawn dishwashing liquid when I bathe our dogs. They are outside pets so they only get a bath maybe once a month or when they decide to roll in something dead. I wouldn't use the Dawn any more often than that because it may dry out their skin but it really does work to kill fleas! I hope this helps!