Shortcode is shown, can it be removed?

My theme, Restaurante from Templatic, is using this function:

// Excerpt length
function bm_better_excerpt($length, $ellipsis) {
$text = get_the_content();
$text = strip_tags($text);
$text = substr($text, 0, $length);
$text = substr($text, 0, strrpos($text, " "));
$text = $text.$ellipsis;
return $text;
}

My problem is that it sometimes writes shortcode in plain text on the archive page, example:

Nu har vi en liten fin kaffemaskin ocks?! V?lkommen! [caption id=”attachment_3011″ align=”alignleft” …

From: https://helensglutenfria.se/nyheter

Is there a way to make sure it doesn’t cut off in the middle of a shortcode, or any other simple solution?