Can you update a clone?

Not sure if this is the right room of the forum for this question, is making a bootable clone part of backup and recovery?
Anyway, my issue is that I made a clone over a month ago anticipating that my drive might fail. I'm running Win7 64bit and Event viewer shows two different events during times of instability: source-disk: The driver detected a controller error on \Device\Harddisk1\DR1 and source-atapi: The driver detected a controller error on \Device\Ide\IdePort1. The instability is intermittent plus I have an XP partition on a seperate drive I can boot from, so I didn't immediately swap to my third hard drive (that drive one was cloned to). Now the errors are back with more frequency but my clone is over a month out of date.
Do I have to re-clone drive one to drive three before I swap them out, or is there a way to update just the differences? What is the best way to handle this?
Thanks for your time.