Preheat oven to 350 degrees F (175 degrees C). Line 24 cupcake cups with paper cupcake liners.
Beat cake mix, 3/4 cup lemonade concentrate, egg whites, water, and vegetable oil together in a bowl with an electric mixer at low speed for about 30 seconds. Increase speed to medium and continue beating until you have a smooth batter, about 1 minute more. Spoon batter into liners to about 2/3-full.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 25 minutes. Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
Beat confectioners' sugar, butter, 2 tablespoons lemonade concentrate, salt, and red food coloring in a bowl with a mixer until smooth and even in color; spread over cooled cupcakes.
