How to Keep an Earth

Mars used to be Just like Earth today. But it lost most of its life because it cooled down, thus its tectonic activity produced less carbon dioxide to warm the planet up. How do you keep Earth or Endako from ending up this way?

    There is a way to keep this from happening. For a decent fee, if you're really worried about this happening, you can move your planet to become a moon of larger host planet, preferably a gas-giant. This way, while rotating and orbiting the host-planet, It's large mass will have the gravity to be constantly manipulating your moon's crust and mantle. This will cause constant fluxuation in tectonic and volcanic activity. Just take a look at Io around Jupiter. It's small size says it should have cooled down billions of years ago, but it is actually Solaris' (Earth's system) most volcanically-active body. Why? Because Jupiter's gravity is acting like a cement truck. It constantly churns the moon's mantle to keep it liuified in addition to friction keeping it warm.

     Another benefit of turning into the moon of a gas-giant is that the host-planet's magnetosphere is a surplus in protection from solar radiation, in addition to protecting you from asteroids by deflecting them or gobbling them up!

     The down side is that, because you're even more protected from solar radiation, your species will evolve with weaker skin. Plus you're gonna have to deal with frequent earthquakes and eclipses. Planetary eclipses are actually pretty, and Endako can deal with earthquakes since its people live in the sky. Some climate changes may occur due to your moon's change of distance from its star.

     There's my suggestion.