You can replace the disk or create new disk and copy the NFA data on to the new disk. You have to follow the below procedure.
1. Stop all the service in NFA machine which starts either with "CA" or with "NetQoS" name.
2. Stop IIS Admin service from services.msc window.
3. Move all the folders from the present drive to Temporary folder which is present in different drive.
For example: If your present installation folder is D:\CA\NFA, move this folder to some temporary folder in different drive, say G:\CA\NFA
4. Install new drive now and chance the Drive letter to D:
5. Copy the contents back to D:\CA\NFA
6. Restart all the services that has been stopped earlier.