T.W.
Calcium comes in so many things like dark green veggies, cheese, etc. You can also get her to have milk by putting it in a sippy cup, in morning cereal (oatmeal, Cream of Wheat, etc.), even at lunch and dinner (a lot of meals contain milk or milk products).
Really right now, what she is getting now is quite a bit, so you really only have to look at replacing her milk when she gives up the bottle entirely. You may find that when the bottle is not in the mix she may just drink it out of a glass. Make it a habit and just put it out at every meal and see how it goes. Another option is to get the kids multi-vitamin that has extra calcium in it if you are worried.
Good luck and don't stress it too much.