My 14 month stopped drinking milk for the last 3 weeks as I tried to transition him from bottle to cup?

I had this problem with my niece and the way we stopped her from always needing the bottle was that we put some lemon juice in her milk in the bottle and not in the milk in her sippy cup, she soon began to realize that the milk in the bottle was not to her liking and the sippy cup was this only took 3 days and she stopped with the bottle all together.