Ok maybe i dont have a clue but Reason also works with Parts or Clips, u can have variations and simply copy a certain clip and paste wherever u want to.
So lets say that at the beginning my bass has a certain midi arrangement, and the last beat goes down an oct. Simply copy just that clip and paste again has u wish wherever and to whatever Instrument. So you dont need to actually redo the entire midi data in the piano roll view.
I suggest you read the manual.