Officially, apt-get update ; apt-get dist-upgrade, after adding the new repos to /etc/apt/sources.list

Described here: https://www.debian.org/releases/stable/i386/release-notes/ch-upgrading.html

Unofficially, both R-Pi I’ve done this to have seemed to work fine, but now have trouble getting

to 48hours uptime. I’ve re-imaged one, and will do the other when I can be bothered.

Bill