Yield: 18 servings (3 points per serving for blue, green and purple)
Preheat oven to 325 degrees F.
Add the cake mix and diet 7UP to a mixing bowl. Use a hand held mixer on medium speed for two minutes.
Zest 1/2 of the lemon and add it to the cake batter. Add the raspberries and mix it together with a spoon.
Spray a 9x13 baking pan with no-stick cooking spray. Add the cake batter and bake for 34-38 minutes.
Let cake cool completely.
Zest the other 1/2 of the lemon and add it to the Cool Whip. Stir together then spread evenly over the cake.