My 15 yr old is doing sleepaway camp for 2 weeks (it's a camp she's done since she was 9 and this is the last year). CIT for probably 2 weeks at a local nature camp. All of August will be marching band.
If she still likes the sports, maybe volunteer with one of those camps?
If she likes the outdoors, check out The Youth Conservation Corps - it places teens in state or national parks to work for a few weeks (state program) or longer (national program)
https://www.dcr.virginia.gov/state-parks/youth-conservation-corps
https://www.nps.gov/subjects/youthprograms/ycc.htm
Locally, other than volunteering at a camp, might be hard to find a service activity that fills a lot of time in summer.