There is a limit to reuse... sorta.
The salts leach out the water, but along with that comes many other substances.
So, you end up with stuff that looks like salt, but isn't salt (or it is, just not NaCl)
I feel you should be able to reuse it a few times, but dispose of it when it starts turning color or smelling.
I am sure there are ways to dissolve the salt, pour out the other stuff, then evaporate the water to get back pure salt again. I haven't done it.
Thanks for that advice, I am always impressed at your wealth of knowledge.