Thanks to Reb for passing along this sound advice from Angela Hursch about marketing to what can be a very tricky audience: teens. Take a look at this short video, Boost Teen Library Attendance, and see how many of these things you are already doing, and if there are any you might like to implement.
If you are interested in starting a Teen Advisory Group as Angela suggests, take a look at the IFLS resource Teen Advisory Groups, and if you want to talk through it any more, let me know!