Preheat oven to 375 degrees F. Line a square 8" baking pan with parchment paper. Butter the sides and bottom of lined pan. Set aside.
In a medium mixing bowl, stir together cherries, cornstarch and lemon juice.
In a large mixing bowl, stir together melted butter and sugar. Add flour, baking soda, baking powder and salt and stir with a fork until the mixture resembles crumbs.
Reserve 3/4 cup of the crumb mixture and press the remaining crumb mixture into the bottom of prepared pan.
Place the cherries on top of the crust.
Sprinkle remaining crumb mixture over cherries. Sprinkle sugar over crumb topping.
Bake bars for 23 to 25 minutes OR until the top is golden. Cool completely before cutting.