using .clone() make th and td elements code example
Example: jquery duplicate last table row
var $tableBody = $('#tbl').find("tbody"),
$trLast = $tableBody.find("tr:last"),
$trNew = $trLast.clone();
$trLast.after($trNew);
var $tableBody = $('#tbl').find("tbody"),
$trLast = $tableBody.find("tr:last"),
$trNew = $trLast.clone();
$trLast.after($trNew);