If you want the newest of the new for LibreOffice, you can place the ppa onto your computer:
https://launchpad.net/~libreoffice/+archive/ppa
Once you click on this link, read the section called "Adding this PPA to your system" to make sure you install it correctly for your 12.04 system.
If this package is to 'cutting edge', I would use the following ppa for LibreOffice that might help as well:
sudo add-apt-repository ppa:libreoffice/ppa
sudo apt-get update
sudo apt-get upgrade
To look over the instructions, follow this link here: https://wiki.ubuntu.com/LibreOffice
To quote the site on what this ppa is about:
LibreOffice test builds and backports
Most of the packages in this ppa have only experienced minor testing
-- in fact it is the place to enable a wider audience to test packages before they are published into the distro proper. In general this ppa
is not for the average user to install without a closer look (if it
would be, its packages would be in the main repositories).
In general, users are adviced to take a look at the changelog for the
details about a package. If there is a specific bug that is intended
to be addressed by an update released into the ppa, you are encouraged
to test, if the update solves that problem. Packages published after
the distro release are mostly such specific fixes. Critical fixes will
SRUed into the main repositories after testing anyway (later, with
more testing).
See also: