Are shop cards drawn after stages reshuffled or dicarded?

[Plain Old Bob 2]

My group is unsure if after drawing and choosing which shop cards to keep after each stage if the cards not chosen should be reshuffled back into the shop deck or removed.  Owning all the expansions gives us a large enough pool of shop cards that it seems we could discard, but I'm assuming we are supposed to reshuffle, as otherwise you would run out of cards to draw if for example you only owned the base set.

[Volkren 153]

I would say that yes, they are reshuffled. This because it doesn't say anywhere in the RtL Rules, but if I recall correctly, in the traditional game, when playing campaign mode, you needed to reshuffle the deck...although I can't find it where does it says so...wierd...

 

Anyway, for example I don't reshuffle the cards, because as you, I own all of the expansions, so it could be pretty annoying to get the same card in a deck that has more than 50 cards. I have house ruled this if you ask me, I think it is better because of the amount of items.