You can do the listing of your packages with dpkg (should work in kde like unity).
alter "/path/to/file/<filename>" to define what the output file (your list of packages) is called and where it is stored on your filesystems.
sudo dpkg --get-selections > /path/to/file/<filename>
To update a newly installed sysem use,
alter the path and filename to match the first code above.
sudo dpkg --set-selections < /path/to/file/<filename>
sudo apt-get install dselect
dselect when used correctly will download and install all the previously installed packages as defined by your list.