I love Kali so naturally I put NetHunter 1 on my old Nexus 7 tablet and used it for a while but then NetHunter 2 came along and didn't really offer a upgrade path from 1 to 2. Everything was geared to first installs. Lucky for me the process to do so was really easy if you already put NetHunter on your tablet.
Basically all I had to do was put the new NetHunter zip file downloaded from
HERE on the root of the sdcard and boot into Fastboot mode "From a powered down stat press and hold the power + volume down buttons" Then selected recovery mode and used teamwin loader "It was still setup from when I first setup NetHunter 1" to install the zip from sdcard and poof NetHunter was updated to the latest. I did lose all data but I don't keep anything on it so that was no big deal.
The one hang up I have found so far is you need to get pciutils for wifite to work. Just run the following command:
apt-get install pciutils
Thank you and happy hacking
OP:
http://aahideaway.blogspot.com/2016/01/upgrading-to-nethunter-2-on-nexus-7.html