Preparation Bring first 4 ingredients to boil in large saucepan, stirring constantly to dissolve sugar and cornstarch. Add blueberries and jelly. Bring to boil. Reduce heat to medium-low; simmer until mixture is slightly thickened and reduced to scant 4 cups, stirring frequently, about 30 minutes. Serve warm or at room temperature. Do ahead: Can be made 4 days ahead. Cover and chill. Rewarm sauce before serving, if desired.
Preparation Bring first 4 ingredients to boil in large saucepan, stirring constantly to dissolve sugar and cornstarch. Add blueberries and jelly. Bring to boil. Reduce heat to medium-low; simmer until mixture is slightly thickened and reduced to scant 4 cups, stirring frequently, about 30 minutes. Serve warm or at room temperature. Do ahead: Can be made 4 days ahead. Cover and chill. Rewarm sauce before serving, if desired.