Refusing milk

My 16 month old is refusing milk at home. He has a dairy allergy and has been on soy milk (ped recommended) since 12 months. Same milk, same cup, same everything. Daycare tells us he drinks ALL of his milk with his meals. At home, he takes a couple of sips. He’s not getting even close to the minimum oz intake of milk right now! We follow the same schedule at home, use the same cup, same milk, etc. I don’t know what to do to get him to drink more so he’s getting enough. Ped said he should be getting 16-24 oz a day. Some days he maybe gets 8 and just refuses to drink it.