PREHEAT oven to 350°F. Place cake mix, 1/2 cup of the dry drink mix, 1/2 cup water, the sour cream, eggs, oil and half of the lemon zest in large bowl. Beat with electric mixer on low speed 1 min. Beat on medium speed 4 min. Pour into greased 12-cup fluted tube pan.
BAKE 50 min. or until toothpick inserted near center comes out clean. Cool in pan on wire rack 5 min.; invert cake onto rack. Cool completely.
PLACE cake on serving plate. Mix remaining 1/4 cup dry drink mix and 2 Tbsp. water in medium bowl. Gradually add powdered sugar, stirring with wire whisk until well blended. Drizzle over cake. Spoon blueberries into center and around bottom of cake. Sprinkle with the remaining lemon peel.