R.R.
My 12 yr old was born with milk allergy. We withheld all milk products for 1 yr and the allergy lessoned from all to just unprocessed milk products like ice cream, yogurt and milk.
Letting your allergy child experience the reactions (as long as they're not life threatening) on occasion seems to help them understand and learn how to manage it earlier. When she would ask for ice cream at parties I always asked her if she thought it was a good idea and tried to leave it up to her as much as possible. She learned and just deals with it like brushing her teeth or any other routine now.