Yeah, it's frustrating, going to miss days because I cannot keep on top of when every 24 hours transpires ...
I have not been voting at the exact time every day but it's been working out okay.
When I go to the
link to vote I see a button with either "Thank you for voting!" (that means I voted in last 24 hours or before they've reset it, don't know the exact algorithm) or "Vote for this story" (that means I can vote again).
If you vote from the same computer each time then I think this should work.
I could not keep track of it if I had to actually keep track of 24 hour periods.

Anyway, I hope this works for others - I don't know what I'm doing differently to make this happen for me.