Preheat oven to 400°. In a 2-quart baking dish, toss together the blueberries, apricot preserves and juice. In a medium mixing bowl, lightly stir together cornbread mix, egg and milk just until combined. Spoon cornbread batter over blueberry mixture and spread evenly; sprinkle with sugar, if desired. Bake until top is firm and lightly browned and blueberries are bubbly, about 20 minutes. Serve warm or at room temperature.