Stir together 1 cup mashed fresh blueberries, sugar, water, and dried lavender in a saucepan, and bring to a simmer over medium. Simmer, stirring occasionally, 20 minutes. Pour through a fine wire-mesh strainer, discarding solids. Cool completely, about 45 minutes. Stir desired amount into 1 serving of Champagne Punch. Garnish with blueberries or lavender sprigs.