Preheat oven to 350°F. Combine preserves and allspice in a small saucepan; cook over medium heat until melted and smooth. In a medium bowl, combine flour, oats, brown sugar and baking soda. Cut butter into flour mixture using a pastry cutter or two forks until the mixture resembles coarse crumbs. Set aside about ½ cup of flour mixture. Press the remaining flour mixture firmly into a 9x9 baking dish, then spread preserves evenly over base and sprinkle reserved ½ cup of flour mixture over the top. Bake for about 30 minutes or until top is golden brown. Let cool and cut into bars.
