Some schools will let you re-use LORS from the previous admissions cycle and some will not. If you don't get in, let your recommenders know, and that way you can give them warning that you would like to request a recommendation from them again for the next cycle.
My advice is to get a "fresh" LOR. That way, your recommenders can address what you've done to improve your application, as well as comment on how you are dedicated to pursuing pharmacy.