wp_list_categories Issue

I wonder if anyone could shed some light for me. I have updated wordpress and one of my plugins has stopped working, which is also up to date. I have narrowed it down to exactly what isnt working the following :-

<li class="cat-item cat-item-49">
<a href="/category/industries/energy/">Energy</a>
</li>

Should look like :-

<li class="cat-item cat-item-49">
<a class="data-post-taxonomy-category" data-post-taxonomy="category" href="/category/industries/energy/">
</li>

This whole plugin works on using the class and data attribute so without these none of the JS is working either. However as it is only WP that has updated I assume something has changed in the wp_list_categories function? It is the following line of code that does changes the category links to contain the correct data :-

$args = array(
    'taxonomy'     => $filter,
    'orderby'      => 'name',
    'show_count'   => $this->get_option('show_count'),
    'pad_counts'   => 0,
    'hierarchical' => 1,
    'title_li'     => '',
    'hide_empty'   => 0,
    'echo'       => 0
);
$content = wp_list_categories( $args );
$content = preg_replace('|<a href="(.+?)">(.+?)</a>|i', '<a href="$1" data-post-taxonomy="'.$filter.'" class="data-post-taxonomy-'.$filter.'"><i class="icon-check-empty"></i>&nbsp;$2</a>', $content);
return $content;

Is there any reason why the preg_replace would stop working in the plugin code on a WP upgrade? Still working fine on the old version.

Any information would be greatly appreciated.

Thanks in advance J