Milk question.

I have a stash of frozen breastmilk and I'm completely done pumping. My son takes one bottle of 2oz cow milk and 6oz breastmilk every night before bed. I'm starting to get to the bottom of my stash and I'm not sure if I should give him less each night and just wean him off bottles completely or give him all cows milk or water it down? What would you guys do?