Not that I'm aware of and I would seriously doubt it. While Disney sells earrings and stuff (because hello money!) I once asked about a belly-button ring and a cast member quickly informed me that "Mickey doesn't believe in piercings!" Probably just meant body piercings and not ears but again...doubt they would actually do the piercings.
My suggestion...do it after the vacation! With the cleaning she will have to do to take good care of them and the sweating and possible jerky rides, her ears will be so sore and irritated! Not to mention you will need to lug around the washing stuff in order to fit in the required 2-3 cleanings per day!! Let her pick out a few cute pairs of earrings at Disney that she can wear after hers heal!
My boyfriend recently got his ears pierced and he got annoyed at the cleaning situation, and he wasn't in a theme park! Just another personal experience tip!
Hope I helped!
(I have 10 ear piercings and my nose...just to let you know that I'm pretty qualified to answer lol)