S.B.
Generally speaking, having him not drink liquids before bedtime is not going to help - not at this age, anyways. Chances are, he is just going to have to outgrow this. A bed wetting alarm may help, but it depends on the kid (helped mine somewhat). It seems like some kids are more prone to having this issue. My pediatrician said that she believe that kids are at higher risk who:
Are generally bigger than other kids their age
Snore or suffer from sleeping issues
Had a parent who wet the bed
Have ezcema
She said there are no real statistics to back these up, just what she has encountered in her practice.
She also reminded me that my daughter wasn't going to graduate and still be wetting the bed and that this too shall pass. In the meantime, stock up on GoodNights and try not to stress about it.
Good luck :)