MIX sugar and cornstarch in medium saucepan. Gradually stir in water until blended. Bring to boil on medium heat, stirring constantly; cook and stir 1 min. Remove from heat. Add dry gelatin mix; stir 2 min. until completely dissolved. Stir in fruit.
FILL crust with fruit mixture. Refrigerate 3 hours or until filling is firm.
TOP with COOL WHIP just before serving.