Can I Recreate RAID1 without losing Data

I have a HP ProLiant DL160 G5 Server which came with a RAID1 controller. I have created two RAID1 pairs (configured the RAID even before OS was installed) with 4x750GB hard drives. Now, we are planning to add a HP StorageWorks MSA60 Hard Drive Enclosure and add 4 more hard drives of 1TB each. When I looked for the RAID controller options, all I can do is, I have to remove the existing RAID controller, and add a HP Smart Array P800 RAID Controller to the PCIE slot.

Now my question is, if I replace the storage controller, how do I configure the RAID1 pairs so that data on my old hard drives still stay on them? Is it possible at all?

Thanks,
Sandeep