Sprinkle gelatin over water in a saucepan.
Allow to soften for 5 minutes.
Heat to boiling, stirring to dissolve gelatin.
Remove from heat; then stir in limeade until thawed.
Add extra water to make 2 cup (500 mL) of liquid.
Allow to cool but not set.
Meanwhile, chill a bowl and electric beaters.
Measure 1/2 cup (125 mL) of the lime liquid into the chilled bowl; then add the nondairy whipped-topping mix.
Beat until thoroughly mixed.
Place in freezer of refrigerator, and chill thoroughly.
Place remaining lime liquid in refrigerator to set.
Beat lime-whipped topping mixture until stiff peaks form. (Re-chill if necessary.) Fold set lime gelatin and lime whipped topping mixture together.