Each case is evaluated by your probation officer, the DA and the Judge. They could decide to keep you on the same terms with no additional punishment or they could send you back to the camp. Contact your attorney and let them know you may fail so they can try to head this off before any recomendations are made. Proof of your grades, attendance and compliance with all other terms will help but since your original charge was drug related and the violation is drug related you might not get off without some additional punishment.
If you test dirty, you will most likely face sanctions. As the previous answer informed you, there is a range of consequences, depending on the recommendation from the prosecutor and probation. It sounds like you've made progress with school, but you've only been out of camp for four months with a potentially dirty test. Given that your underlying case was for drugs, you might benefit from an additional rehab program of some sort. Talk to your previous attorney and discuss the specifics of this recent development so that he/she can properly prepare for a probation violation.
If you fail your drug test, you will be in violation of your probation for at least two reasons, failure to
Remain law abiding and failure to abstain from drug use. But, you will also be in violation if you do not show up. Marijuana can be detected in your system for quite a while after use, for chronic users, over a month.
Your probation officer has broad discretion on what to do with you, including taking you back into custody where you will appear before a judge on the violation.
Any comments offered are not intended as legal advice. This attorney does not know the specifics of the particular case sufficiently to offer legal advice. You should hire a lawyer who can evaluate the details of your specific situation before offering advice.