Took me a little bit more time to figure out how to upgrade recovery to version 18.104.22.168.
So far I discovered 2 possible approaches and like to share it with you:
1. Following the instructions within the original TWRP thread (http://forum.xda-developers.com/show....php?t=2449679).
This requires the TWRP Manager app from the Play Store. Install TWRP Manager, open it and provide root permissions. Then hit Advanced->Install Recovery.
Downside of this approach is that the TWRP Manager app requires you to install Stericson BusyBox. Since I didn't want to mess with an other already installed Busybox version, I looked for another approach
2. Flash new version through TWRP recovery itself. This is probably the most simple/straight approach.
Download zip version of TWRP 22.214.171.124 (e.g. from http://techerrata.com/browse/twrp2/g2d802)
Save it in phone memory. Reboot in recovery and flash zip the usual way.
I did use the second approach, which worked flawless.