Hi! Mugs can be re-filled at POFQ and POR food courts. I know I can't remember all the drinks, but I'll try to give you some and perhaps we can get some help along the way from other folks!
Coke, Diet Coke, Sprite, Caffeine Free Diet Coke (I think), Pink Lemonade, Fruit Punch, Root Beer, Dr. Pepper, Fanta Orange, iced tea, coffee, hot chocolate
My DD's helped me with this, it's been a few weeks now and our memories are foggy!