In a large pitcher or mixing bowl, combine the Countrytime Lemonade Mix with 4 cups of cold water. Stir vigorously until the powder is completely dissolved.
Pour the chilled pineapple juice into the lemonade mixture. Stir well to combine.
Transfer the lemonade-pineapple mixture to a large clear beverage dispenser. Add the chilled Sprite and gently stir to mix. Drop in the lemon slices and plenty of ice.
Pour into glasses over additional ice, if desired. Garnish each glass with a fresh lemon slice for extra flair.