Thats what the plugin is doing, reread it please.
Though on our script vote is once per 24 hours. And you can vote again once a new day is reached.
So the plugin displays the time until midnight basicly, which is when ppl can vote again.
Valid voting is not individual on a per human being, as that would require to intense database information, so the script allows voting again on a new day, as long as the user have not voted on this day. I also know of no other script which handle it differently because of the heavy database use if you do so
What i could do so, is integrate the same thing into the "vote message" plugin, which displays a "you voted for xx" box once the user votes. It would properbly better fit into there