Its a tough line to balance. The goal should be to convince them that its good for them and they can be apart of something special. It can be hard if you're at a small school and team successes are few and far between. I know we use the goals of the Team State Duals to keep kids out. It could be a difficult thing for some schools but try and find an attainable goal for the team and make them feel like an integral part to that plan.
These are things we have done in this situation and have had some success in keeping kids out.
That being said we have also gone the other way done everything we could and they just don't react at some point you have to be able to realize you did all you could and its not worth you're time to pursue it any more.