First thing's first. Open the terminal and enter the following command:
sudo apt-get remove google-earth-stable
Now, that takes care of uninstalling Google Earth. Next, let's add a Google Earth PPA Repository to your system:
In the terminal, copy and paste these commands:
wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add
sudo sh -c 'echo "deb http://dl.google.com/linux/earth/deb/ stable main" >> /etc/apt/sources.list.d/google.list'
sudo apt-get update
sudo apt-get install google-earth-stable
Now you won't have to worry about your Google Earth getting out of date. Now that you have this repository, updates to Google earth will come alongside your other system updates.