I've been dealing with this recently and I've used the Raid Flea Spray which kills them instantly and the eggs up to 4 months. I also read that Pine Sol mixed with water can be sprayed out in the yard and I also use the Cutter Bug Spray which you spray using the hose - it kills mosquitos fleas and other bugs. I searched online for easy ways to help rid my house and the Dawn Blue Dish Soap is good for combing the jpets and dunking the fleas into hot hot water with Dawn in it - kills them instantly. I'll bathe them with the Dawn but only occasionally.
Lavender works too so I use the Fabuloso Lavender for mopping my floors. It has helped.
Good luck!