Pour the chilled Sprite into a large, shallow dish or baking pan, spreading it out evenly.
Place the dish into the freezer and set a timer for 1 hour.
After an hour, remove the dish from the freezer and use a fork or spatula to scrape and stir the semi-frozen mixture, breaking up any ice crystals.
Return the dish to the freezer and repeat the scraping and stirring process every 30 minutes for the next 30 to 45 minutes, until the mixture is evenly slushy and smooth in texture.
Once the mixture is fully frozen with a scoopable, icy consistency, give it one final stir to ensure even distribution.
Serve the Sprite slushie immediately in glasses, with a straw if desired, for a refreshingly icy treat.