I have been blessed with an exceptional xbmc openelec setup for the past year, which i use in coordination with my Synology NAS to watch movies and series at home. After one year though i decided to upgrade my 3x Openelec version to the latest one. This is a short guide on how to do this, if your unix commands are on average. FYI, the below are based on knowledge found in many forums and troubleshooting pages.

1. Make sure you download the latest openelec release from the official web site.  Choose Raspberry Pi builds, and then select your the release you like (i selected [Diskimage] OpenELEC Stable – Raspberry Pi ARM Version:4.2.1). Unzip the release and copy the copy KERNEL, KERNEL.md5, SYSTEM and SYSTEM.md5 from the target folder.
2. Make sure you access openelec from the network using UNC (\\192.168.1.30). In order to do so, enable SAMBA from the openelec settings. Copy the copied files from #1 inside to the update folder. (\\192.168.1.30\update). In my case i go the error that there was not enough space for the new files to be copied, even though the SD card is a 32Gig SD.  If you did not get any error, then you are done, restart openelec and you are upgraded. If you got the not enough space error though, proceed to next step, to increase the space on the storage of the openelec.
3. Referenced from here, I opened an ssh connection to my openelec using putty. Pretty simple process if you have not done that before. Use “root” as username, “openelec” as password. Type the following :

Switch to root partition

1. cd /        

Keep xbmc from restarting

1. touch /var/lock/xbmc.disabled

Stop XBMC, so we can unmount /storage

  killall -9 xbmc.bin
  umount /storage

If you get an error on the above command that means that the storage cannot be un-mount, because some other process is using it.

Run the below to see what process is using the storage and write down the numbers of them. lets say 871 and 9131

fuser -m /storage

Now kill them!!!, and unmount storage.

kill -9 871 and 9131 && umount /storage

Alternatively you could also use the “top” command to see what these processes are.

Once you have killed all processes that use storage and unmounted it, run the following:

Verify mounts:

mount
parted /dev/mmcblk0

Change to dislpay sectors:

unit s

 Show partitions, make note of starting sector of your partition

p

remove the partition

rm 2

recreate it using same starting sector number and ending in “-1” to use remaining space:

mkpart primary 258048 -1
quit parted
e2fsck -f /dev/mmcblk0p2
resize2fs /dev/mmcblk0p2
mount /dev/mmcblk0p2 /storage
df -h
rm /var/lock/xbmc.disabled

Reference Pages:

http://wiki.openelec.tv/index.php?title=Updating_OpenELEC

https://raspberrypi.stackexchange.com/questions/8625/resize-file-system-on-openelec