So, what I tried to do is: Stay as close as possible to Katy's original recipe. She postet a written recipe and even filmed a "how to" video

The only thing I changed was replacing the cows butter with vegan butter. I used the Earth Balance, it comes in a cube-shaped tub and in my opinion is really close to what non-vegan butter tastes like. Also as I didn't have fresh cherries, I used canned ones. Didn't make a difference in my opinion as you bring them to boil anyways. 
Now, my version of the cherry pie is cruelty-free. I don't know how Katy Perry thinks about veganism but she should try it. You get the same taste, the same flavors and you don't higher your cholesterol level. Milk and any other forms of dairy products clog your arteries because dairy is always coming with a lot of saturated fat. It's not good for your cardiovascular system. The vegan butter alternative is made of oils from plants, so it's made out of unsaturated fats. 

Right now, there is a lot of advertisement happening to promote dairy. But don't let them fool you. Inform yourself
Here comes my recipe of a cruelty-free vegan cherry pie. Bon Appetit!
Ingredients for the crust:
2 1/2 cups all purpose flour (I think you could even use spelt flour)
1 cup vegan butter (e.g. Earth Balance)
1/2 cup ice cold water
Ingredients for the filling:
6 cups cherries (fresh or canned, probably even frozen)
2 Tablespoons vegan butter
3/4 cups sugar (or brown sugar)
2 Tablespoons Water
3 Tablespoons Cornstarch 
Directions:
Combine flour and vegan butter with your hands until you feel like the dough is too dry (moist sand) and then slowly add the water, one spoon at a time. When the dough is sticky enough to stay together, form two balls, form a disk and wrap them into cellophane foil. Refrigerate while preparing the filling.
Heat 2 Tablespoons of the vegan butter in a pan on moderate heat and add the sugar and simmer. Stir around. When the sugar is dissolved, add all the cherries. Combine Cornstarch and Water in a little bowl until the cornstarch is completely dissolved. Add it to the cherries and bring them to a boil. Stir and let it boil for another 2 minutes so that the starch can thicken the cherries. Set aside and let it cool while you prepare the crust.
Preheat the oven to 350-375°F.
Roll out the first disk of dough until its big enough to be the base in your pie plate (about 9-inch). Roll out the other disk of dough and cut long stripes with a knife. These ones will form the lattice on top of the pie. Add the cherry filling into the pie pan and decorate with the dough stripes in the typical pie-lattice shape.
Bake the pie for about 50-60 minutes. Let it cool or serve warm. Listen to Katy Perry songs. Optional: Add vanilla ice-cream. Bon Appetit.