To store the leftover grilled prosciutto pizza, place it in an airtight container or wrap it tightly with plastic wrap, and then refrigerate it for up to 3 days. When you're ready to reheat, place the pizza slices in a preheated oven at 375°F (190°C) for about 10 minutes, or until they're hot and the cheese is bubbly. Alternatively, for a crispier crust, you can reheat the slices in a skillet over medium heat until warmed through, which should take about 5 minutes per side.