Just invest your extra 15% wisely, and remake your local world in a left-handed friendly fashion. I've heard that part of the reason for the lower lifespan is increased accidents among lefties due to the clear favoritism for right-handers in the world (one might say reality has a clear right-handed bias).

But, I'm left-handed and not too worried about it. If it were a dramatic difference in lifespan, I guess we'd be even fewer in number than we are.