I found a glitch. If you regenerate your pets at the plaza, afterwards it will say, regen pets for 0 gold.
If your pets die again, you can go here and click it and it's free.
I do not want anyone using this to their advantage.

Thanks for reading,
Aspxct

(Edit: Sorry it was a visual glitch, it was paying, yet didn't show how much it would cost!)

A lot of the site's pages will work this way. It is always a good idea to reload or freshly enter a feature before interacting with it. If you're looking at a "stale" page, its information very likely could have changed since the time it was first loaded.