To Make Ice Ring: In a large ring-shaped plastic container, arrange lemon and lime slices in a decorative pattern along the bottom. Fill with just enough water to cover and freeze for at least 4 hours, or until solid.
To Make Punch: Dip ice ring mold in warm water to loosen. Remove ice ring and place into a large punch bowl. Pour in the grape juice, lemon juice and lemon-lime soda. Stir gently and serve.