for summer of 2014 I suggest wildwood theater- quality shows in Rockville area- this summer they are doing Grease and NINE- see website here
http://wst.org/
also keep your eye on greenbelt theater, and KAT Kensington arts theater.
Also, Alden community theater in McLean and if you don't mind driving - the teen program at synetic in crystal city is amazing!! It's like joining a fitness bootcamp for theater.
If she's not a singer, I don't recommend auditioning for, but if she wants to attend great shows check out young artists of America at Strathmore- they have a summer show with camp, then a show in November and March- only ONE performance each because these are huge productions with a large orchestra, so the cost is too much to put them on more than once.
Also, watch Goldstar.com for deals on tickets to local shows.
break a leg!