She might really like a spa treatment at either SSR or GF- they have massages, facials, mani/pedis, etc. Sounds like a fun "girly/grown up" thing for a teen. You could even do a "Girls morning" at the Spa at GF, then do the Tea in the afternoon for all the ladies in your group.
If she's a more sporty type, there are lots of great activities around WDW- parasailing, water skiing, watercraft rental, horseback riding, bike rental, golf- something for just about every taste.
Hope she has a great time and finds a fun activity or 2 to do.