The problem with twiddling with Mother Nature is that in such an orbital modification, chaos theory - one again - predicts the possibility of a planetary wild card.
The orbits of other planets could be destabilized if we decided to change Earth's zip code. And, the solar system, which lives on the brink of dynamical chaos, could come unglued.
So it might be more prudent just to terraform Mars and relocate to it, rather than modifying the Earth's orbit. And, billions of years from now terraform Titan - which will be a balmy place under the glare of a bloated red giant sun.
Asteroid 2011 CQ1 is so small it is unlikely ever to been seen coming this close to Earth again. But asteroids are like mass transit buses. If you miss one, another one will eventually come along.