It's a bit more complicated than falling and missing. Getting out of the gravity well takes the same amount of energy as you gain from falling into it, so those

It's a bit more complicated than falling and missing. Getting out of the gravity well takes the same amount of energy as you gain from falling into it, so those two things alone would be pointless. I'm not an astrophysicist but I think you have to do it in such a way that you "steal" some of the planet's orbital momentum.