The fleas may not be all over the house. Fleas can nest in certain areas, particularly where the animal lays. Find those areas and spray. I had two areas in my current place and it was a while before I found the second place. Once I found it, I've had very few problems with fleas. This place could be under a bed or couch, in a closet, or whever you cat decides to park his or royal self.

Change bedding and blankets that they sleep on. And so on.

If you 'bomb' your house, you have to seal everything that can be a food container or surface and then wash everything else, including wiping counters and such off. aurie is correct. Cats are very sensitive to chemicals. Since cats rub everything in sight, it is important to clean all surfaces your cats may touch.

In one place I lived, I had an exterminator come in. It was easier. We had to be out of the home for 1 hour and he didn't bomb. I did protect food services, but it wasn't that extensive. His stuff was more lethal for the flea but dissipated and deactivated after 1 hour and was much safer.

The fleas could also be under the home and attracted to a water source.

Good luck.

Anne