So, I built my nether reactor out of a bunch of gold and diamonds I had been storing to see what it does. It was pretty crazy; after I activated it I warped to the netherworld version of my land and was attacked by the zombie pigmen and promptly died (serves me right for activating it unprepared!)
Now I have a giant obsidian tower in my world that seems to serve no purpose. Nothing special spawns inside it regardless of the time of day, it just sits there taking up space. I didn't get to keep anything I scavenged when I entered the nether because I died while in there and my stuff didn't seem to remain when I returned to the reactor location.
So, do I need to rebuild the whole reactor again just to re-enter the nether, or is there a way to re-activate the reactor once it's done its thing already? Is it a one time thing?