Heat two cups water to boiling. Stir in gelatin and sugar until dissolved. Transfer to a large pitcher. Add two cups cold water, fruit juices and lemonade concentrate. Stir until lemonade concentrate thaws and thoroughly combines.
Just before serving, place mixture in punch bowl. Spoon in sherbet and pour in Sprite. Serve immediately.
I would not recommend making the gelatin mixture the day before, because if it sits in the refrigerator for that long, it may begin to set up.