Heat oven to 375°F. Spray 11x7-inch (2-quart) glass baking dish with cooking spray.
In 1-cup measuring cup, mix raspberry and rhubarb liquids. If necessary, add enough water to make 1 cup. In 2-quart saucepan, mix 1/2 cup sugar, 1/2 teaspoon cinnamon and the cornstarch; stir in reserved liquid. Cook over medium heat 4 to 5 minutes, stirring constantly, until thickened; remove from heat. Stir in raspberries and rhubarb. Spoon into baking dish.
Unroll dough; place over raspberry-rhubarb mixture, tuck in edges. Brush with melted butter. In small bowl, mix 2 teaspoons sugar, 1/2 teaspoon cinnamon and the pecans; sprinkle evenly over dough.
Bake 18 to 24 minutes or until bubbly and golden brown. Cool 5 minutes. Cut into 4 rows by 3 rows. Serve with ice cream.