So I, like any good person with internet access, googled "rescue dried gel eyeliner" and got tons of hits. Most of them were useless (like, close the jar every time you use it to help it not dry out - uh, yeah, thanks for that piece of brilliance) but a few were helpful.
It seems there are two main ways to do it: adding a liquid (glycerin, eye drops, water, mixing medium, etc) or heating it (blow dryer, microwave, hot water, etc).
Original gel liners:
Sequins Blue Velvet
You can tell how dried up Sequins is by the reflection off the top, Blue Velvet is more moist and squishy. Sequins has also shrunken a bit so it's pulled away from the sides of the container, and it has a crack running through it.
I pulled out my hair dryer and heated it. I used the High Hot setting and heated it from each side along with underneath. That damn thing got hot! So if you do this be careful and don't burn yourself! Opening it up with a towel, I saw this...
Hrmm. Not much different. I touched it and it was a little softer, but not much. Huh. At this point, I can't remember how long I needed to heat it, and I was too lazy to find the video again, so I opted to try another method!
I put the pot in a baggie and put it in hot water. I let it sit for 10-15 minutes and then pulled it out. It was fairly warm but not impressively so. I opened it up and it looked about the same. I touched it and it felt about the same. Hrmm. Let's try another method!
Just stick the end of a brush in there and mash the hell out of it!
And brute force wins by a landslide!
Here are the links I read/watched, just in case you want to check them out!
Blog Posts I found (in no particular order)
Strawberry Makeup Bag: How To Rescue Dried Out Gel Liner (Inglot Duraline)
Beaut.ie: How To Rescue Dried-Out Gel Eyeliner (Makeup Store mixing liquid)
YouTube Videos (no particular order)
AshleyNicollette: Reviving Dried Out Gel Eyeliner (warm water)
EnKoreMakeup: Dried-up Gel Liner? Revive it! (mixing medium and primer + heat)
Missmakeupnerd: Save your DRY gel eye liner!!! (warm water)
And if you use a spoon to mash the gel liner back into the pot, don't just put it in the sink in case someone else happens upon it and tries to clean it and ends up with black eye liner all over the sponge, hands, soap bottle, and sink. Just saying.
Any tricks you've tried to rescue dried out gel eyeliner?