You can refill them, but why?
By the time they dry up the tips are usually shot or pretty close anyway.
And, like a brand new pair of socks, at least for me, feel so darn good when you open up a new set!!
For me, they are an inexpensive item that is worth every penny to replace when you need new. I keep my old dried up ones for bleaching.
But, there is a thread somewhere on the items you need to refill. Just search the forum, it'll show up........I remember glycerin, water and something else or two that needs to be mixed up and put in with a dropper, after you gently remove the tip.
Where in SoCal are you?
Valerie