Install the flatpak package of LibreOffice will give you the latest version. You can do this via software center. Just as @Forpli said uninstall the current version first.
By terminal you can uninstall Libreoffice like this:
sudo apt remove --purge libreoffice-common
sudo apt autoremove
To install the latest (flatpak) by terminal;
flatpak install flathub org.libreoffice.LibreOffice