Depends on the goal. If maximizing quality and length of life under constrained resources, prevention is more effective. But, as you mention, prevention does have inherent limits on life span. Biotechnology could allow further, perhaps infinite extension to lifespan.
I'm not sure this is a good goal to have. To paraphrase Jobs in his Stanford Convocation speech, death allows the clearing of old ideas and provides urgency to motivate the living. Further, the infinite-living "you" would no longer really be "you", since all the matter and its organisation would be replaced several times over. (Biologically, this also happens but at a different scale so the organisation is more preserved). Arguably, your own ideas, thoughts, and concept of self remain.
I'm not sure this is a good goal to have. To paraphrase Jobs in his Stanford Convocation speech, death allows the clearing of old ideas and provides urgency to motivate the living. Further, the infinite-living "you" would no longer really be "you", since all the matter and its organisation would be replaced several times over. (Biologically, this also happens but at a different scale so the organisation is more preserved). Arguably, your own ideas, thoughts, and concept of self remain.