Combine blueberries, grape juice and allspice in a medium saucepan. Bring to a boil; reduce heat and simmer 2 minutes, stirring occasionally. Pour mixture into an 8-inch square baking dish coated with cooking spray. Combine next 5 ingredients in a small bowl; stir in margarine until mixture is crumbly. Sprinkle topping over blueberry mixture; bake at 350° for 25 to 30 minutes. Serve hot or at room temperature. Yield: 6 servings.