My cat is nursing and has fleas! Help!!

Hi! My cat is currently nursing her singleton kitten right now and it is 2 days old. Two weeks ago we gave my cat frontline plus but the dose was administered off center from her neck and she was able to lick it all off. Complete user error. Everyday since we gave her the dose, I’ve still been combing fleas off of her (not an infestation but maybe 5-10 fleas a day) When is it safe to re-dose her, keeping her safety and the kittens in mind?