You can install Google Earth Pro to auto-update.
Download Google Earth Pro for desktop
If you need to manually update Google Earth, you can download the most recent 6.2 and 7.x direct installers. Some of the following installers do not auto-update (not recommended).
Download a Google Earth Pro direct installer
The Pro versions of Google Earth 6.0 and earlier are no longer supported. Google Earth Pro 7.1.5 and earlier requires a license key. If you do not have a key, use your email address and the key GEPFREE to sign in.
v7.3.2
v7.3.1
v7.3.0.3832
v7.1.8.3036
Note: By downloading Google Earth from the direct download links above, you're also agreeing to the Google Earth/Maps Terms of Service and Google's Privacy Policy.