http://jsfiddle.net/tigreton/JGNmK/
You can see in the fiddle the code.
It loads the #mod-pregunta and #mod-respuesta divs well. And the link too. But if I click it one more time, it doesn't load anything. What do you think is happening? Thanks
Check out jQuery's live() function to help with this.
It can't load anything, because jsfiddle do not host mod_up_vote.php
However, on your server, try to use .live() or .delegate()
Change
$(".vote1").html("<a href=\"\" title=\""+ id_pregunta + "-"+ id_respuesta + "-1\" class=\"vote1\" id=\""+ id_pregunta + "-"+ id_respuesta + "-1\" name=\"mod_up\">Aceptar</a>");
To
$(".vote1").replaceWith("<a href=\"\" title=\""+ id_pregunta + "-"+ id_respuesta + "-1\" class=\"vote1\" id=\""+ id_pregunta + "-"+ id_respuesta + "-1\" name=\"mod_up\">Aceptar</a>");
And use jQuery live
to attach click
event handler to the above anchor element.