ADD boiling water to gelatin mix in medium bowl; stir 2 min. until completely dissolved. Stir in cold water. Pour into 13x9-inch pan.
REFRIGERATE 4 hours or until firm.
CUT gelatin into 1/2-inch cubes. Reserve 1 cup COOL WHIP for garnish. Layer blueberries, remaining COOL WHIP and gelatin in 8 dessert glasses. Top with reserved COOL WHIP.