Combine the cherries, water, and sugar in a medium saucepan over medium-high heat. Bring to a boil, stirring occasionally, and cook for 10 minutes.
Remove the saucepan from the heat and set it aside to cool to room temperature. Once cooled, strain the mixture through a fine mesh strainer, collecting the liquid in a clean container.
Place the fresh cherry syrup in your refrigerator to chill completely before using.
To Make a Limeade
Fill a large glass with ice. Slowly pour in the lemon-lime soda. Add the fresh cherry syrup and lime juice. Stir gently to combine. Garnish with cherries and lime slices, if desired. Enjoy immediately.
Notes:
The fresh cherry syrup can be made in advance and stored in your refrigerator for 4-5 days. This recipe makes about 1 cup of fresh cherry syrup, which is good for 6-8 drinks.