It's not that simple. If you already have a fusion drive that you built manually, and is DOES have a recovery partition, you should be able to just run the installer. If you had to do some funky stuff to get your original install completed, you may have to repeat those steps. In my case I have a fusion drive built with a SSD and a striped RAID, the installer could not create the recovery partition, and therefore the install failed. This could also apparently occur if you have BootCamp installed. Some suggested reading:
http://apple.com/support/no-recovery