How can i make my 15 months daughter drink milk from a cup or glass. she has got habit of playtex nurser.?

she drinks water from a straw glass even juice from other glas but she refuses to drink milk from any other than nurser. when and how shall i make her leave the habit. today is the 5th day she has not had milk as we are not offering her nurser. tried with simple straw, glass , and spoon .. nothing works. she drinks water in few seconds from same straw glas but throws away milk. i don’t know what to do… she wants to eat from our big dish, likes to use same glass as our for evrything else but not milk..