Carefully spoon raspberries with syrup into 2 ice-cube trays. Add enough water to just cover raspberries. Freeze 3 hours or until firm.
In very large plastic or glass pitcher, mix lemonade concentrate, raspberry juice concentrate and water. Refrigerate until serving time.
Just before serving, stir soda pop into lemonade mixture. Place ice cubes in glasses; pour lemonade mixture over ice. Garnish with lemon slices.