Because reheated coffee is terrible, but disposing of good coffee such a waste, I have taken to repurposing all of my abandoned coffee into a refreshing espresso granita, a trick my elder daughter taught me last summer.
Simply decant a full-sized cafetiere of abandoned (or freshly-brewed) strong coffee into a plastic container suitable for the freezer, and mix in two tablespoons of sugar. Increase the sugar to taste, especially if you are adding more than one cafetiere's worth to the container. Cover, and stick in the freezer. Every few hours - or when you remember - drag the tines of a metal fork through the freezing coffee, separating the granules. If you start the process at breakfast, your granita should be ready come supper.