Sprinkle gelatine over lemonade concentrate in microwavable bowl; let stand 1 minute. Stir. Microwave on HIGH 45 seconds. Stir until gelatine is completely dissolved.
Place blueberries and sugar in blender container.
Add gelatine mixture; cover. Blend until pureed.
Add ice cubes; cover. Blend on high speed until smooth and frosty.
Serve immediately for a soft slush or cover and freeze at least 4 hours for a firmer sorbet.