Place juice in a saucepan over medium-high heat and reduce to 1 cup, about 25 minutes.
Preheat oven to 350°F. Make crust by combining graham cracker crumbs, butter and water in a bowl, stirring until mixture begins to stick together. Press crust mixture into bottom and about 1" up the sides of an 8-inch spring form pan. Bake for 10 minutes. Cool completely.
Combine gelatin and sugar in a bowl. Add the boiling juice reduction to the gelatin mixture and stir until gelatin and sugar are dissolved. Cool, but do not allow gelatin to set up.
Beat the cream cheese and lime zest with an electric mixer until smooth and incorporated. Reduce speed and slowly add gelatin mixture until thoroughly combined.
Fold in light whipped topping by hand using a rubber spatula.
Scrape the filling into prepared crust and distribute evenly.
Chill for 8 hours or overnight. Garnish with fresh berries, if desired, and serve.
Makes 12 servings or (1) 8-inch cake.
Serving size: 4 ounce slice (1/12 of cake)