To make blueberry reduction: In a small saucepan, combine blueberries, sugar and water. Bring to a boil, stirring occasionally. Once boiling mash blueberries. Remove from heat and set aside to cool. Once cool, strain mixture into a container.
In a cocktail shaker filled with ice, combine blueberry reduction, lemon vodka and triple sec. Shake to combine and strain into a martini glass. Add a splash of Sprite and garnish with blueberry skewer. Serve immediately.