Preheat oven to 375°.
Lightly spoon flour into a dry measuring cup, and level with a knife. Combine flour, 1/4 cup granulated sugar, and brown sugar in a bowl; cut in margarine with a pastry blender or 2 knives until mixture resembles coarse meal.
Combine sliced peaches and lemon juice in a large bowl, and toss gently to coat. Add raspberries, 1 tablespoon granulated sugar, and cornstarch, and toss gently. Spoon fruit mixture into an 8-inch square baking dish coated with cooking spray, and drizzle raspberry jam evenly over fruit mixture. Sprinkle with flour mixture. Bake at 375° for 45 minutes or until brown.