Sometime you will have to go in mid November when the Festival of the Masters Art Show is at Downtown Disney. They have allot of the area around World of Disney covered with sidewalk chalk artist drawings, and their work is absolutely awesome. They have artistic activities for the kids, and also artists with tents on the West Side. My neice was 9 when we went in November and loved it.
Sorry, but I'm drawing a blank on what to specifically do in the summer except for the several shops where they sell prints. One attraction she might enjoy is The Magic of Disney Animation at MGM.