Not sure exactly what the issue is ... but the end of breastfeeding can be a challenging time ... also there are certainly kids that do not like much milk and that's okay ... they can get their calcium and other nutrients/vitamins in countless ways ... for dairy lovers like my son and I, several servings of milk, yogurt, cheese etc. are essential every day but that may not be the case for you and your family.
You have a few options ... there are kinds of drinks by all means the pediasure (I think that's what its called) and other drinks work until age 5.
But with that said, milk is cheaper and easier ... perhaps you can taste the formula or the milk ... 1/3 milk to 2/3 formula tastes like formula so that definitely does not mean that she doesn't like cow's milk. I think I stopped mixing after the second time because it didn't taste good (but then again I don't particularly care for formula and doubt most mothers do.)
Try the milk cold or warm ... do like a little game with different small sized cups, with a choice or water or milk or smoothies or soy milk ... (and you may have to do this a few times a month) ... tell her you are making a special treat ... give her a small cup or sippy cup or try it with a straw ... anything to make it seem fun.
My son seemed to have a few weird quirks around that age with juice in bottles he expected to have milk in the bottle not juice ... but he really wanted juice and asked for it ... so that's around the time we started with juice boxes although he had a tough few months with the whole straw coordination thing so he was a bit frustrated and I didn't really understand why he wouldn't drink juice from the bottle but it was just a way to get to the next level (straws and cups and sports bottles ... my son never took to the sippy cup!)
He still actually prefers milk in a bottle but everything else will be in a sports drink container or a straw or a little Dixie cup. And he can tell me what he wants ... it tastes cold and yummy, I want juice, I want water etc.
I just kind of left the milk or juice box or cup there for him and he would get to it after a few minutes ... it may have been a power issue ... I'll drink the milk when I feel like drinking it!
So all I'm saying is don't assume that your daughter does not like cow's milk ... it may be in the presentation, way the milk is given (cup, sippy cup, bottle, juice/milk box, straw or no straw, timing, amt. of milk given or feeling the milk is too-something ... (hot, cold whatever.)
P.
Did you try giving her only milk or a mix of formula and milk?
And if you're a milk drinker or chocolate milk drinker that may be another way to get her to drink because your're drinking it. (I think that's why my son wanted to drink with a straw so badly since I always drink Nes-quik or yogurt with a straw.)