Changing a status of events usually requires multiple event pages and a knowledge on how to handle them with switches and variables.
Timing events also requires the use of parallel processes (the original timer included in eventing has a few disadvantages).
Also, I don't think that you want such a respawn based on minutes - the player would just sit at his PC waiting (and grinding) while doing his homework - better would be to fix the respawn to some actions or the number of steps taken.
If you specify what exactly your problem with the event is so far, we might help more.
If you can't think of a way how to do something, you might want to check some tutorials or sample games on how others solved those problems - in that case just follow the link in my signature.