I think the tantric side of Daoist mysticism/alchemy has semen retention as a way of preserving vital energy, but... as to whether that has its own terminology or not I am also not going to investigate.
I did read a few cultivation webnovels a while ago, and I recall a few jokes to the effect of "The great sage has been furiously seeking immortality in his cave for days now".
Garrett Wang (Harry Kim) and Robert Duncan McNeill (Tom Paris) did a podcast called The Delta Flyers where they do a full episode-by-episode rewatch of Voyager and often rant about the many problems of the show (and about the bits they enjoyed, as well). Didn't get through it all, but it was decent travel listening.
Both of them are pretty often annoyed about how their characters (and most of the others) were stuck on a writing treadmill to obey that absurd syndication demand of an eternal moment, such that new viewers can drop in without feeling like they've missed anything.
Buddhist position of the empty nature of the self based on dialectical materialist epistemology
I'd be quite interested in any texts along these lines you might recommend.
An interesting-ish and anti-verifiable thought about nonexistence is that since we cannot perceive nonexistence or time "while" nonexistent, and all things necessarily change... stretching that then any kind of law or logic or universal pattern that decrees we are dead may also eventually change and we just reappear. No matter the infinite infinities that may need to pass. And not just "an exact duplicate of ourself", but "ourself".
Which is to say: isekai is, alas, inevitable.
I don't think that actually follows. We'd certainly be in a position to practice and refine the process, but not necessarily guarantee that it's working until we give the (apologies for the Harry Potter reference, but I think it apt) Robot House Elf a pistol and turn around. Also, ethics.
Luckily the simple solution is to just not make a sapient slave race, robotic or otherwise. Sapience isn't necessary for an autonomous tool.