I am not sure where to find it but a friend of my daughter did chamber music groups for years. These were small groups of kids of varying ages that would practice together and then showcase them. The groups were all different groups of instruments. They were introduced to it from their music teacher so I have no idea where to look for this.
Do you have school or youth orchestra's, choirs or band in your area? As long as she isn't stressed for time adding another instrument or joining a choir can be a good way to add performance time. And probably be easier to find a group that performs often. How about summer camps? My son attended a jazz camp for a few years and they had pianists in their small groups. The camp was only for junior high kids and older though.
If you are really want your daughter to have something to put on collage apps she should look into the Piano Exams. (It's really young to really worry about college apps yet.) Maybe it's time to look at a different piano teacher? It sounds like you like her piano teacher, but if your daughter really wants to perform more perhaps she had grown out of this teacher and she isn't the best fit for her needs.
