Grease and flour a 13x9x2-inch baking dish. Prepare cake mix as directed on package, except add enough water to 1/3 cup of lemonade concentrate to equal the amount of liquid called for on the cake mix.
Pour cake batter into baking pan.
Bake as directed on cake mix and cool for about 15 minutes.
Mix remaining lemonade concentrate and powdered sugar.
Prick the warm cake with a fork and then drizzle lemonade mixture over cake.