Can you use bay leaves a second time?

Technically, yes. But, it would have picked up all the stuff from your stew, so if you were to then put it in a cream sauce the cream sauce would then taste all stewy. And really, they aren’t that expensive, and it’s kinda gross. You’re kinda getting into a really gross area, like when people buy sheets or underwear used. If you’re really that hard up for spices, you can go to Whole Foods or other health food stores and buy them from the bulk foods section for shockingly cheap. Most of what you’re paying for in a supermarket is the nice little container, anyway.

Grow your own. My grandmother had a Bay Leaf tree…it was huge, Bay leaves for eternity.
I wouldn’t recycle these items for the obvious reasons. Too much risk of bacteria from the soup or stew they were soaked in for hours. A Bay Leaf would not dry out and return to it’s original fresh condition.

I think if you put them into a plastic bag or container and then put them in the freezer, you could most certainly use them over and over. I wouldn’t think there would be a risk of cross contamination if you are putting them into a soup or stew that is simmered/boiled for a prolonged period of time.

As was said though, they are not really expensive items so for convenience I would just chuck them and start over each time.

Once you used them in a stew, most of the flavor wold be gone anyway.

No, they have given up their essence into whatever liquid they were cooked in.