For an extra burst of flavor, try adding a few mint or basil leaves to the blender. Adjust the sweetness to your preference by adding more or less stevia. If you prefer a smoother texture, you can strain the agua fresca through a fine-mesh sieve, but it's not necessary. This agua fresca is best served immediately. If you need to make it ahead, store it in the refrigerator for up to 24 hours, but be aware that the color may fade slightly.