New extrusion
I'm not sure if the Schaeffer furler is the same in this regard as my Hood unit but for my Hood, you would need to buy another tube extrusion (the furler is made up of multiple extrusion pieces, each 5 ft or so long, joined together with splice pieces and rivets). The last extrusion piece at the top is cut to length to fit the boat. In your case you would likely need to remove the last extrusion piece and replace it with another that is cut a few inches longer. Of course you need to determine if there was a reason the old extrusion was cut where it was and not a couple of inches higher. Will the top swivel interfere with anything if it is higher? Will the lead angle from the swivel to the masthead sheave still be within equipment specs?