You could get an identical sized drive, and clone the first drive. Then replace the old one with the clone.
You can use the dd command to copy from one device to another. So it might look like "dd if=/dev/hda of=/dev/hdb bs=256". I just made up the block size, maybe another value would be more efficient. Also, use the "fdisk -l" command to determine what devices the drives actually use.
I am recommending replacing the drive, because if it is going bad, you will lose everything on the drive, so its best to replace it as soon as possible.