Since release, there has been a general cry for some way to invoke using the Gateway. People don't want to lose those coins, after all, and - given the rewards - it's understandable.
PW and Cryptic, for reasons that are also understandable, haven't implemented this. They want people logging in and playing the game.
Sometimes, though, you can't get to a PC to invoke, despite ones best intentions. And *poof* all that work goes up in smoke.
So, this is not a call for a way to invoke using the Gateway to continue to reap celestial coins. Instead, I'd like to suggest that there be a way to 'reset' the timer via the Gateway. Let's call it 'rewardless invoking'. The idea is that a player could reset the 29 hour timer (maybe a 5 min. mini-game? just to avoid bots), but not actually get anything other than the extension to the timer. So, while they don't get anything, they also wouldn't lose anything.
I have no idea how technically feasible this would be, but as the character timer is likely already tied into the Gateway, I can't see it being terribly difficult to do.