Odds of Hanging On
This is a job frequently held by students, so most counselors aren't there for too long. There's always the chance that you decide you really want to become a counselor-4-life, but that's not usually the norm.
Hanging on as a counselor is not necessarily a sure bet. You may have gone into the job with a smile and a great letter of rec...but at some point you'll have to demonstrate that you're actually good at working with children. If you want to stay in the job, take it seriously and really work to make sure kids are enjoying themselves. Always make safety a priority. Nothing will lose the job for you faster than letting little kids put themselves in danger.
If you make friends with the staff, are positive and supportive with the kids, and don't lose anyone in the woods, then you'll have a pretty good shot of staying on for next summer.