I'm an old boat laminator, and I can tell you forget it. I could repair it for me, but it would cost more than a new pot. That's not going to be easy anyway because you're going to have to break the old pot off the bottom of the big mountain and with any luck some pieces of the old pot will be stuck to the bottom of the big mountain. Once you get it cleaned up so it will sit flat and buy a new ceramic pot to your tastes, consider not gluing it altogether. It will be easier to move even though I'm sure you won't be moving it very often. Before you assemble the new pot with the mountains you need to make sure your new pot doesn't wobble. If your four-footed pot rocks on three feet, fix it, -or else. I would speculate that the old pot didn't set perfectly flat and putting mountains on opposite ends of the pot put stress on the pot like the weights on a tetter-totter. No ceramic will bear that for long. To fix feet that rock you need some two part epoxy. Put a thin piece plastic film like a plastic baggie on a dead flat surface, put a dab of mixed epoxy on the plastic film and set the pot on the flat surface with the short foot touching down on the gob of wet epoxy, let it set up and cure for a day or two and carve it to look right. It may not be forever, but it will work OK for some time.