The rules are very clear that you cannot conduct business twice at the same settlement on the same preprogrammed set of moves. You cannot do so even by leaving the settlement and coming back to it.
I also recommend playing Himalaya with 4. That is really the number of players it is designed for.
Well I'm glad I read this thread... I forgot this rule and have played it 3 or 4 times already. Even with this rule wrong I love it, but I think it will definitely be better with the rule correct!
My game group will never let my live this down... its another in the long line of games played incorrectly. Don't even ask how many times it took to play Liberte correctly!