How about this:
    // Call native refresh method on ajax datatables
    if ($.fn.DataTable.fnIsDataTable($table[0]) && $table.dataTable().fnSettings().sAjaxSource) {
      $.each($.fn.dataTable.fnTables(), function() {
        $(this).dataTable().fnSettings().sAjaxSource && $(this).unblock().dataTable().fnDraw();
      });
    }