Well, the long and short is, you can't. Because Latisse is a prescription it comes in a specific pack with specific directions. There are about 90 drops of Latisse in a 3ml bottle, and less applicators than that (60). Especially if you follow the one applicator per eye per night plan. I advise my patients to do it differently (because really, do you have two bottles of mascara, one for each eye??) and to use the applicators twice before disposing. And in all reality, I have some people who use only one applicator for the entire bottle. Keep the brush clean and this shouldn't be a problem. You could contact the office where you get your Rx and see if they have any extra brushes, or you can get your next Rx and conserve the brushes better! But you can't just get extra brushes. Sorry.