Preheat a grill to low, using a combination of charcoal and fruitwood chips, if possible. In a medium bowl, combine ½ cup water with the brown sugar, mustard, paprika, chili powder, salt, gelatin and Worcestershire sauce. Spread the spice paste all over the ribs and grill over indirect heat for 2½ hours.
Meanwhile, in a medium saucepan, combine the apple juice, honey and butter and cook over medium heat until the butter melts.
Cut eight 12-inch-long sheets of foil. Pour one-quarter of the butter mixture onto the center of each sheet, top with a rack of the grilled ribs, meaty side down, and crimp the foil to enclose; wrap with another sheet of foil. Repeat with the remaining ribs. Grill the packets, meaty side down, for 1 hour. Unwrap the ribs and grill, meaty side up, for 30 minutes more.
Meanwhile, stir together the barbecue sauce, apricot preserves and ¼ cup water; brush the ribs with the glaze and grill, meaty side up, until very tender, 20 minutes longer. Transfer to a cutting board and cut into individual ribs, brushing with the remaining apricot glaze.