Preheat the oven to 350 F. Place one pie crust into a lightly greased round 9-inch pie plate. In a large bowl, mix pie filling with blueberries, sugar, and cornstarch.
Add the filling to the pie crust and top with the other pie crust. Seal edges with a fork. Cut four slits into the top of the pie. Bake for 45-50 minutes.