"Huna ta new visa naliye pani hunchha, because I will be back in the US before my current visa expires." This will definitely put u in trouble at the port of entry, if ur visa is expiring soon. So, better to get a new visa while u travel Nepal.
The hand-written passport is good until 2015 for travelling according to the ICAO rules.
<http://www.myrepublica.com/portal/index.php?action=news_details&news_id=15113>