Hello, newbalert here.

Is it possible while deckbuilding, to discard a card I paid 2 experience for (level 2 card), and then re-gain the experience for that card, to be used on a different card?

Thanks

Nope. Once XP are spent, they're gone.

The only thing close to that is upgrading a card that already has an xp cost that has the same name.

So for example Shriveling.

I could have a L0 Shriveling and spend 5xp to make it L5.

Or I could have a L0 Shriveling, spend 3xp to make it L3. Then at a later point, I could spend an additional 2XP to make that L3 a L5.

That's not quite getting the xp back, its more like having paid part of the cost (and getting part of the benefit) already.

I believe the only cards like this at the moment are Shriveling and Aquinnah (although I could be missing one).

28 minutes ago, Jobu said:

I believe the only cards like this at the moment are Shriveling and Aquinnah (although I could be missing one).

You haven't. Only these 2 have more than one level 1+ version at different levels (Strange Solution has multiple versions at the same level, and they can't be upgraded into one another, per their text). It's likely that more cards like that will come out, though.

contrary to the others if you want too then no one will stop you. I am happy to do exactly that between scenarios and regard it as my char adjusting their equipment (hmmm that last mission I was short on ammo so next time I will bring more) saying that I haven't needed to yet and the more I play the less I seem concerned with what is in the deck.

if you want to play exactly by the rules then there is a card in one of the early Dunwich packs that allows you to swap and replace cards of equal xp value. If I remember correctly...

If you're thinking of Adaptable (which costs 1 XP itself), it only lets you swap 2 level-0 cards for free between scenarios (normal rules have each swap cost 1 XP).

should be enough though? The more I play the more I seem to concentrate on playing and the less on deck building.

It doesn't do what the OP was asking about (replacing level 1+ cards with others).

ah, apologies assumptions can sometimes cause more trouble than they are worth..