We had a real bath and shower hater for a long time, so we stopped giving them. May sound gross, but she was fine and eventually we were able add them back in. Our daughter preferred to shower with one of us (still does prefer that for the most part), and we gradually started talking about getting hair wet and hair washing. Honestly it took quite a long time before she was taking a fairly regular bath, but now (at 3.5) she'll happily wash hair in the shower, stay in the shower herself, and take a bath (or sometimes use the bathtub as a swimming pool).
You might try a shower instead of a bath or getting in the bath with her yourself. We also had a lot of luck in general when she was younger with telling stores about a lion or a giraffe that had the same fear as her and was able to tackle it.