How about a backstage, behind the scenes tour?
I bet she'd think it was really neat being able to go to some of the backstage parts of Disneyworld and see things many people never get to see.

They offer a number of tours that allow children.
Or maybe a special dinner at one of the more "grown up" restaurants. I know when I was her age, I always loved when my parents took my brother and I to a nice restaurant and we got to dress up.
Another possibility is to set up something special through Gifts of a Lifetime. Maybe a park scavenger hunt?
Then there are always the just around the resort and parks things.

Renting boats on Disney's lakes, horseback riding and carriage rides at Fort Wilderness.
Have a great trip!