While I realize I may be asking a rather stupid question, I am unsure about the upgrading procedure. I got 2.1.3.7 running, however, I'd like to flash Mautz' new 3.0.0.8 image with TWRP (no Multirom, though!). So, what do I need to do?

Can I just start TWRP and flash the new image on top of everything else? Do I need to wipe anything? Do I even need to start from the top and install CM13 again? Is there is possibility to retain my homedir?