If the bully has been sent for retraining, that will most likely put a stop to it. Bullies continue to bully until there is some sort of intervention, even if they are just interviewed about it. Nearly all bullies suffer from a lack of self esteem and bullying the weak is a way that they can make themselves feel better about themselves. As soon as someone stands up to them, they back off. Your daughter may even find that the bully keeps his/her distance as they won't like to be reminded of, in this case, your daughter's challenge. Bullies hardly ever go in for 'revenge'. They just find someone else to bully.