You can try a rosemary flea dip. Two cups of fresh rosemary in boiling water for half an hour. Strain the liquid, and a gallon of warm water, and once cool pour over your pet allowing it to dry naturally.
Brewers Yease tablets in your dogs food. This works it way out through the dogs skin and fleas do not like it. Sort of like garlic to humans.
You can also wash your pet and apply some lavender essential oil to the base of the tail and at the neck.