Line bottom and sides of a 13- x 9-inch pan with aluminum foil, allowing 2 to 3 inches to extend over sides; lightly grease foil.
Stir together cake mix and oats in a large bowl. Stir in butter with a fork until mixture is crumbly and dry ingredients are moistened. Press half of oat mixture evenly onto bottom of prepared pan.
Stir together peanut butter and preserves in a medium bowl. Gently spread peanut butter mixture evenly over oat mixture in pan. Sprinkle peanuts and remaining half of oat mixture evenly over peanut butter mixture.
Bake at 375° for 30 minutes or until top is golden brown. Let cool in pan on a wire rack 1 hour or until completely cool.
Lift baked bars from pan, using foil sides as handles. Place on a cutting board, and cut into 24 bars.
