Stir together whipping cream or half-and-half, sugar, and vanilla until sugar is dissolved. Place silicone ghost mold on small tray. Pour cream mixture into molds. Cover with plastic wrap, freeze for 6 hours or overnight until firm.
In a large punch bowl, combine berry or apple juice, grape-juice concentrate, and lemon-lime carbonated beverage. Remove cream ghosts from mold by inverting and peeling the mold away from the frozen cream mixture. Place on a chilled tray lined with plastic wrap or waxed paper. Add mouths and eyes with black decorating gel.
Use a spatula to place ghosts in the punch bowl. Serve immediately.