In a large saucepan, combine sugar, water, and strawberry flavored gelatin. Boil for 3 minutes. Stir in pineapple juice, lemon juice, and orange juice. Divide mixture in half, and freeze in 2 separate containers
When ready to serve, place the frozen contents of one container in a punch bowl, and stir in 1 bottle of lemon-lime soda until slushy.