Surely the pepti jr has calcium? Or do you mean when he goes off that?
My ds is allergic to dairy also, he gets his calcium from rice milk. I offer milk or water as a drink during the day and he normally chooses the rice milk which is great because I don't have to worry about trying to get calcium into him lol.
When he was younger he wouldn't drink much rice milk and then he would have soy yoghurt, soy icecream, and rice milk in porridge and that covered it