The phrase "to get a refill" means to get more of something, usually a beverage, when the original amount has finished or is almost finished. Full definition
Maybe I will just get a refill of my soda and sit here and people watch for awhile. (breastfeedingneeds.com)
Potions can be replenished by a certain degree per save point visit - you'll have to wait if you need to get a refill on several of them. (gamerstemple.com)
There are actually little plastic trays that you can even just get refills for. (pawprintsthemagazine.com)