I typically install LMS onto a logical volume which doesn't map to a specific disk. I can then add more space to that LV as required (e.g. by adding more disks to the LV pool). If you have done this, then it should be trivial to add a new drive to increase your capacity.

If not, then you will need to replace the current drive with the larger one, then reinstall LMS onto that new drive. You can then restore the previous data into the new installation.