You are issued 1 year because your client letter might state you have 12 month contract or so.I have the same situation like you I got H1B for 16 month. Going Nepal and getting H1B stamped you will only get the visa for 1 year or so and again you have to get visa when you go next time. I would suggest better to go Nepal when you get next H1B renewal if you are not in hurry. Just my suggestion.