The article Translate your website to another language over on CodeProject includes the Punjabi language code ("pa") in it's enumeration of languages so I am making the leap here that if you follow that tutorial you should get Punjabi support.
or using the code generated in the link you provided in the comments you could add pa to the included languages of the code generated i.e.
<div id="google_translate_element"></div><script type="text/javascript">
function googleTranslateElementInit() {
new google.translate.TranslateElement({
pageLanguage: 'en',
includedLanguages: 'de,fr,hi,it,pa', // <- insert pa here
layout: google.translate.TranslateElement.InlineLayout.SIMPLE
}, 'google_translate_element');
}
Note the above is speculative as I have not tested the code but I believe it's highly unlikely that google would drop support for a language.