<?php

// Assuming the date you're looking for is January 2:
$when = 'January 2';

// Verbose method:
if(($date = strtotime($when)) < time()) {
  $date = strtotime('+1 year', $date);
}

// If you need this as a one-liner...
$date = (strtotime($when) < time()) ? strtotime('+1 year', strtotime($when)) : strtotime($when);
echo date('m/d/Y', $date);