Why does it need to reload? Why not just have the votey button hyperlink to a dummy fragment URI like "#upvote_comment_1234", and something like a ping attribute [1] to send a request in the background, and a CSS rule like

  a.votey:visited { visibility:hidden; }

to hide the button once you've clicked it?

[1] https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#...