This one is from my daughter.
I was putting away a glue stick and complained aloud about how they always get dried up before they're used up. My daughter simply said, "why don't you put them in a plastic bag?" Yes, why don't I, brilliant daughter?! A simple solution staring me in the face, but I never thought of it.
So, my 2 new glue sticks for this year. I put them in a freezer bag, forced all of the air out, sealed shut and rolled up tightly.
Hoping this will keep these glue sticks usable for their entire contents. Maybe next year, I won't have to buy new glue sticks!
For those already dried out glue sticks
I don't know if this will work with really, rock-hard, dried out glue sticks. But with glue sticks that still feel flexible, but just won't lay down a strip of glue on paper, this worked for me.
I had two, older, semi-dried out glue sticks that I revived. I took the caps off, and put them in a plastic baggie with a damp paper towel, then sealed the bag up. I left them on the counter for 24 hours. And voila, they were good as new. These glues sticks wouldn't leave a streak of glue on paper before, but now are working just fine.
My plan is to just keep all of my glue sticks in a sealed bag. They won't get misplaced, and will hopefully get completely used up before they can dry out. I likely won't need to buy new glue sticks for a couple more years, now.