Something similar to the league reset, similar to how it's currently done for medals might not be a bad idea.
At a periodic frequency, the leader-board can be reset. As soon as there's a war, and if there's a glory change (win or loss), the current glory points can be come into effect (similar to how the league placement happens as soon as at least one battle is done after the periodic league reset).
Probably worth considering, instead of trying to re-invent the wheel.
Cheers and happy gaming!