Sprinkle dry cake mix on top of filling, leaving approximately 1/2 inch open at the top. With a spoon, lightly sprinkle the melted butter over the dry cake mix, until all the dry mix has butter on it. You can spread it a little with the spoon.
Bake at 350° for 20-23 minutes, or just until the tops are light golden brown.
Remove from oven and let cool completely before you put the lids on.
Leave the covered jars at room temperature for a day or two, or stick them in the refrigerator.
Notes
Alternative topping method: stir the cake mix and butter together in a bowl. Crumble topping over cherry filling in jars.