Cream butter and sugar until light; add eggs and beat until light and fluffy.
Sift together the baking soda and sifted flour, and add to the creamed butter mixture, alternating with 1/2 cup of the lemonade concentrate. Stir in grated lemon peel.
Drop dough by teaspoonfuls, 2 inches apart, onto ungreased baking sheets. Bake cookies for 8 minutes or until lightly browned around edges.
Brush hot cookies with remaining lemonade concentrate, then sprinkle with a little granulated sugar. Remove cookies to racks.