I've kept WLT Perique in its previously opened bag in the fridge for a year or more. I remove as much air as possible, and clamp it shut with clothespins. Sometimes, I see increased yeast growth (dull, yellowish smudges), but this is most likely just the Pichia anomala that makes Perique into Perique.
I have some bags of WLT Perique that were shipped vacuum sealed, and left unopened in those bags for several years, with no problem.
I've actually found it much less fuss to just open a fresh bag of Perique, spread out all of it to dry for a couple of days, then bag the still whole leaves.
Bob