Wash and drain blueberries. In a medium saucepan, combine the sugar, 1 cup of berries, cornstarch (use heaping tablespoons with frozen berries), salt, water, cinnamon and lemon juice. Cook and stir over medium heat until thick. Remove from heat.
Immediately add butter and remaining berries. Stir until sauce is mixed with all of the berries and butter is melted. Pour mixture into prepared pie shell. Keep refrigerated till serving time. Serve with whipped topping or ice cream.