  That drive is no longer a "hot-spare". It is now a fully-functioning member of the array. You don't currently have a hot-spare. It is also possible to have two hot-spares configured.   No, Reconfigure will EXPAND a virtual disk, usually by adding a physical disk to it. So, if you currently have a 3-disk RAID 5, you insert a new drive, and run the reconfigure, you could reconfigure your 3-disk RAID 5 to a 4-disk RAID 5 (adding a disk's worth of storage space to your array/server) or a 4-disk RAID 6 (essentially a RAID 5 with a hot-spare but instead of the hot-spare being a non-participating member - a standyby-only drive - the hot-spare is integrated with the array as a full member; the RAID array produces an extra amount of parity so that two disks may fail while maintaining the availability of the array, rather than waiting for a drive to fail before it starts rebuilding to become a full member of the array; RAID 6 is usually preferable when using very large drives). 
I've scoured through postings and think I almost have the solution, but would like either confirmation or correction if possible. Have a PowerEdge R310, four 500 gb drives, RAID 5, with one of those drives set as Global Hot Spare.  One of the drives (003) failed, hot spare did it's job and kept the RAID going. Put in the replacement drive in and can see it's Ready on Physical Drives through Open Manage.  In addition I see it listed under Virtual Drives as a Non-Raid virtual Drive.   I thought that it was automatically rebuild the RAID after the drive was inserted, but it didn't.  I started the Reconfigure on the existing RAID, hoping to choose the new drive and begin the rebuild, but it didn't see the new drive as a physical drive.  I'm assuming it's because the system assigned the new drive as a new virtual drive. Do I delete the new virtual drive, then run the reconfigure on the existing RAID 5 virtual drive to add the new drive? Hope this makes sense and I appreciate any help!  Right now my server is up and fine, but these 500 gb drives are reliable - I lost another one late last year and replaced it. 
Adding a replacement hot swap drive back into a RAID 5 (PERC S300)