Relatively simple suggestion: Allow multiple refills per day, at increasing costs each time.
Currently refills are 25 points. A second refill could cost 4x that to 100, then 4x that to 400, etc. (I like round numbers, but the costs could be different, of course).
The second refill is still good value, and some players would use 3+ refills per day possibly during wars etc. Great way to remove points from the game.
EDIT: Since this wasn't clear to some, this still resets daily. So, say you want to refill energy and nerve one day that's 25 + 25 points. The next day maybe you want to refill energy twice and nerve once, that would cost 25 (1st E refill) + 100 (2nd E refill) + 25 (1st nerve refill). Hope that's more clear.