I'd make it so that we can make tech that could slow aging down, reduce the mortality to zero thanks to a making an apparatus implanted into all people's digestive systems that could take a large amount of resources and convert them into something us humans can consume without threat to our bodies. It could be configured to account for allergies and adjust the kind of energy produced and distributed throughout the body.
With food and water needs eliminated, my next main focus would be preserving the human species beyond Earth. I would evaluate what can be done on Mars, the kind of tech that can take us to there, but if it doesn't work, we revert to trying some sort of travel to another planet far, far away that could support life. While we don't send all, we send a considerable amount of competent men and women on this expedition to help make the human race's fate to be not tied to that of Earth's.
I would ensure that I can stay ruler of the country via copying the contents of my brain to an insane amount of servers and PC's to where a benevolent authoritarian ruler's benevolence can't be tampered with by the lesser values of a successor, much like when going from King Solomon to Rehoboam.