F you want to keep your eyelash extensions lashes looking full and fabulous you will need a infill every 2 5wks approx depending on what set of lashes is applied and the time between infills will depend on your natural lash cycle and what length and thickness of lash is applied and how you have looked after your lashes caring for your lashes is simple treat them with care no rubbing and follow the aftercare advice given infills prices are offered when you have about 50 of your lashes remain