Certbot 0.10.2 isn’t the version from the Ubuntu PPA; it’s the version from Debian’s jessie-backports repository. If it was installed from jessie-backports, a normal apt-get upgrade will upgrade it to the latest version from there (which is currently 0.10.2, which you already have).
Check https://backports.debian.org/Instructions/ to confirm that you have jessie-backports enabled.
If you need a newer version than the one in jessie-backports, you can uninstall it and install certbot-auto instead (though note that you’ll have to set up your own renewal cron job then).
Since Ubuntu PPAs aren’t designed to work on Debian, I wouldn’t recommend trying to update it from there.