Considering that evolution essentially requires the gene pool to be constantly adapted to ever changing environment and circumstances, you sound even more suicidal on the species level. You will selfishly be hogging the resources, that your newer replacements(children) would need. And replacements there must be, since you yourself may not be best equipped to survive in a warmer planer or a world with more carbon mono-oxide. But there you will be, using artificial methods to hang on. As long as you live, you will be consuming resources, and therefore competing with and risking the survival of the children. That is not to say that your life has no value or that you should kill yourself at the earliest, but once you have raised your kids, once you are past your prime age to be an active contributor in general, it is time to let go. Medicine should be focusing on removing diseases and pain, not curing or postponing natural death. You should be enjoying a healthy life, not necessarily a very long one. If you really do actually love your children and their children that is.