I wouldn't reuse them, BUT when we bought our mugs at Pop in April the cashier specifically told us they were good for refills "for life." Her words, in responce to my husband's question ensuring they were good for the whole week we were there. There were many, many, many people using what were obviously very old mugs, from many different resorts and I never saw anyone stop them. I'm not saying it's right, but it would seem that most people here care more about it than Disney does.