I'd recommend using uupdate
from devscripts
and build the package like the original was build before.
Install required packages
$ sudo apt-get install build-essential devscripts
Download the the old package from official repository (will use MediaWiki
as example) and the new tar-ball from upstream.
$ mkdir ~/Downloads/mediawiki
$ cd ~/Downloads/mediawiki
$ apt-get source mediawiki
$ wget https://releases.wikimedia.org/mediawiki/1.26/mediawiki-1.26.0.tar.gz
Run uupdate
to create a new source folder from the upstream tar-ball and the old debian/control
$ cd mediawiki-1.19.14+dfsg # depends on your Ubuntu version
$ uupdate ../mediawiki-1.26.0.tar.gz 1.26.0
$ cd ../mediawiki-1.26.0
Now you should check if you need to make changes to debian/control
etc files. If you're done you can build the deb package and install it
$ dpkg-buildpackage -us -uc
$ cd ..
$ sudo dpkg -i *.deb
progB
manually too...