I know first hand how frustrating and disappointing it is to have leaders leave after such a short commitment. There's no ONE way to keep leaders--I believe it's a combination of several intentional actions. (1) Being choosy with you have join your team. (2) Giving them clear and doable expectations of what's expected. (3) Providing them occasional coaching/feedback regarding their roles. (4) Being liberal with praise and letters of encouragement. (5) Building a community of relationships that they don't want to leave.

These are not simple tasks! Developing leaders takes constant attention. People typically don't leave a youth ministry team when their return is greater than what they give. If you are a leader of leaders, it's crucial they get constant attention and feedback, or they will leave. Great question Timothy!

http://www.simplyyouthministry.com/community-articles-doug-s-thoughts.html