You will probably have to pull the cells apart, they are typically lightly welded. Just be carefull if ya get the urge to use a pry tool, you don't want to short across a button head and the outer case of a cell. Just stay calm and be careful, you can do it.

Be sure and have a got hot soldering iron as you build them back up as side by sides. A good hot iron will allow quick soldering, actually putting less heat into the cells.