A simple DOM Parser
and an strtr()
will solve this...
$dom = new DOMDocument;
$dom->loadHTML($html);
$arrLi = array();
foreach ($dom->getElementsByTagName('li') as $tag) {
$arrLi[$tag->nodeValue]="<a href='#'><span>$tag->nodeValue</span></a>";
}
echo $html = strtr($html,$arrLi);