[shka]

One option - you build your link on plugin level. Than you have to choose a hook, when $threadinfo already exists. Example with "showthread_complete"

    <plugin active="1" executionorder="5">
			<title>Button Plus</title>
			<hookname>showthread_complete</hookname>
			<phpcode><![CDATA[if (THIS_SCRIPT == 'showthread'){
$threadidid = $threadinfo['threadid'];
$new_thread_link = '<div><a href="refresh.php?'.$sessionurl.'do=newthread&amp;t='.$threadidid.'" rel="nofollow" class="newcontent_textcontrol" id="newthreadlink_top" style="margin-left:10px;"><span>+</span> '.$post_phrase.'</a></div>';

    $find = '<div id="pagination_top"';
    $replace = $new_thread_link.$find;
    $vbulletin->templatecache['SHOWTHREAD'] = str_replace($find, $replace, $vbulletin->templatecache['SHOWTHREAD']);
}]]></phpcode>
		</plugin>