I am advised that an update is available but can not be done Automatically.
Should I uninstall the previous version before installing the new download?
It depends on you current LibreOffice version. What is your current LibreOffice version and on which version would you like to migrate? What Windows version?
If you plan to upgrade to new version inside the same 3.5.x, 3.6.x, 4.0.x or 4.1.x series then there is no need to uninstall LibreOffice before installing update. But if you would like to install latest version of LibreOffice, but you currently have some old LibreOffice version, then first uninstall current old version before installing new one.
Not much help. If I uninstall do I lose any files I have already created?