// Here $id comes from SQL after submit data
<div class="comment'.$id.'"><ul>

// new comment

</ul></div>

complete: function(data){
var ID = $(this).attr('id').replace('comment','');
$(".comment"+ID).append(data.responseText);
$(".comment"+ID).fadeIn(2000);
}

$(".repfrm").click(function(){
error.fadeOut();
if(checkForm()){
var author = inputAuthor.attr("value");
var url = inputUrl.attr("value");
var img = inputImg.attr("value");
var replycom = inputReplycom.attr("value");
var parent_id = inputparent_id.attr("value");
var tutid = inputTutid.attr("value");

        $.ajax({
        type: "POST", url: "comment.php", data: "action=insert&author="+ author + "&replycom="+ replycom + "&url="+ url + "&img="+ img + "&parent_id="+ parent_id + "&tutid="+ tutid,

            complete: function(data){
error.fadeOut();
var ID = $(this).attr('id').replace('comment','');
$(".comment"+ID).append(data.responseText);
$(".comment"+ID).fadeIn(2000);


});
}
});
    }
    else //alert("Please fill all fields!");
error_message();
});