In a large saucepan, combine the sugar, cornstarch and water until smooth. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in gelatin until dissolved.
Divide mixture in half. Stir blueberries and lemon juice into one portion; spread over crust. Chill until set. Gently fold raspberries into remaining gelatin mixture; cool to room temperature and set aside.
Meanwhile, in a small bowl, beat cream cheese and confectioners' sugar until smooth. Fold in whipped topping; spread over blueberry layer. Chill until set, about 2 hours.
Carefully spread raspberry mixture over cream cheese layer. Chill for at least 4 hours. Yield: 8 servings.