A couple of different things could happen depending on your judge, prosecutor, and probation officer. Some will see it as a serious violation and your probation could be revoked and the original sentence imposed.  Other judges/prosecutors will view you as potentially having a drinking problem and may decide to extend your current probation instead and then require you to attend some type of counseling.  Regardless of which option is used, you will want to try to work it so that the two cases run together, instead of stacking.  At least this way, you'll minimize the effect of the new arrest.  It's good that you are getting a lawyer.  Try to make sure you get someone that has worked with the prosecuting office before who may know of other programs for young offenders that could be offered in your jurisdiction.  As a word of caution, the judge might be patient with one new offense.... but he'll be less patient if you pick up another new charge.  So be careful not to reoffend while you are getting this new MIP worked out.