The refill button is for those that have already purchased a brewed coffee, iced coffee, or iced tea. If someone isn't a gold member, they get charged $0.54 (at least in my store). If they are a gold member, the refill is free. They have to have bought it today, and policy is to show receipt because the stickers don't show dates. IIRC (I'm a former barista), the hot coffee and iced coffee refill buttons are on the bottom right of the brewed tab, and the iced tea refill button should be under the tea tab in the bottom right corner. The brewed coffee refill button is brown, the iced coffee refill button is blue, and I think the tea refill button is blue as well. It might be yellow. Regardless, they should all be in the bottom right corners :)