It's badly etoliated (stretching to get more sun) and appears to be in a soil with too much organic matter.
The poor dear needs heaps more sun, and soil that doesn't retain much, if any water.
(I have a few lithops. I'm shocked yours is still alive!)
The problem with some succulents is they will appear alive, but actually already have one foot in the grave. It laying down without any grip into the soil might mean the taproot is gone.
When you repot it, take your time, and check that it's tap root is intact. It's ok to let it sit out in the open for a day or two - any damage should scab over. (And after repotting, let it alone for a week or so before offering it a drink)
If there is a taproot - you're good to go, but if there is little to no root, chances are slim it will survive. There are methods to encourage a new taproot, but that is (currently) above my knowledge level. (AKA I've never been able to get them to grow a new taproot.)