Installing updates

I struggle with installing your updates.... all the instructions/installation guides cover new installations... I have a setup that works but I get lost when I try to install an update... it would be very helpful if you provided us with a useful guide for installing a new version... right now I am under the impression that my whole current setup will have to be reconstructed from scratch if I install an update... I've got way too much time invested in getting subsonic set the way I like it to go thru all that again... help please