Royal Caribbean does not have liquor or beer in their mini bars. They contain soft drinks, bottled water, and snacks. The snacks are quite expensive and not worth it in my opinion. The soft drinks and water cost the same as at any bar. No matter where you are on the ship all the sodas, bottled water, liquor, beer, and wine has the same price.
Your cabin attendant will restock it as needed and of course charge you for anything used.