Heat oven to 375°F for shiny metal pans (or 350°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups.
In small bowl, gently toss 2 tablespoons of the dry cake mix with 1 1/2 cups blueberries to coat; set aside.
In large bowl, beat remaining cake mix, water, oil, lemon peel, eggs and cream cheese with electric mixer on low speed 30 seconds. Beat on medium speed 2 minutes, scraping bowl occasionally. Fold blueberry mixture into batter. Divide batter evenly among muffin cups.
Bake 18 to 22 minutes or until tops are light golden brown. Cool 5 minutes; remove from pan to cooling rack. Cool completely, about 1 hour.
In medium bowl, beat powdered sugar, butter, 1 teaspoon lemon peel, the salt, vanilla and 1 tablespoon milk on high speed about 4 minutes or until smooth and well blended, adding more milk by teaspoonfuls if needed. Frost cupcakes with frosting. Garnish with 1 cup blueberries the lemon peel and mint leaves. Store in airtight container at room temperature.