It was just an idea I don't intend to ever use.
The closest I have to Sufficiently Advanced Aliens you described in a verse of mine is a race of entities who create and run entire universes in the same way human scientists set up and observe bacterial colonies in laboratories. No forever-lasting universe is present here; when one of the observed universes reaches the end of its lifetime, it is collapsed and recycled into a new Big Bang, seeded with life after it has cooled down, then left to its own devices for trillions of years to see in what direction things will go. During the story, they even copy an existing universe to resolve a time paradox.
The entities themselves are non-corporeal and exist outside the universe, so they're not affected by entropy. Aside from being functionally immortal, their temporal perception is also non-linear, so you can get acquainted with one, then travel back in time to before you met, and it will recognize you as if you'd only met a minute ago and not an arbitrary length of time from now.
Anyway, this is the kind of godlike entity I was thinking of when I wrote the OP.
Energy is used in the process, they will eventually give diminishing returns and can even expire, they will just revive no matter what, even if it takes the complete transfiguration of their being to do so, and the process is largely involuntary. Cycling heat back in an area indefinitely would require rotating shifts, and "indefinite" is theoretical. Even though it is an ability they have it might be gone in an eon, since they are always changing.
But as said, mine weren't thought up with the idea of maintaining the universe we know forever, the ability to accomplish great tasks by draining heat in mass was just a funny coincidence I noticed. That, and antagonists who wish to preserve their home, don't care about what detriment they will cause outside of it and have "access" to immortal cosmic beings is a plot line I feel like stealing.
edited 17th Jun '15 11:56:45 AM by IndirectActiveTransport