Heat the cherry juice and red wine with the three bags of mulled wine spice and let it steep for 15 minutes. Remove the mulled wine spice. Then stir in the preserving sugar and cook everything bubbly for 5 minutes. Finally stir in the rum. Immediately fill twist-off glasses that have been rinsed out with hot water, screw them on and turn the glasses upside down for 2-3 minutes. Tastes very good on slices of toast that are still warm.