the only thing i can think of, is if you were to wire brush/sand away the concrete (if we are talking patchy thin concrete thats ok, and if you can get 1 bit up it the concrete is badly dun you may even be able to get something under it and "wall paper strip" it.
but if concrete is thick and well done it becomes completely impractical.
other than that to be honest i think you would have less trouble re-leveling then putting new ones over the top. A pain, and a real shame, also put a boot up the previous owners.
if its any help, the previous owners of my house did something similar and we did manage to salvage it but that was more down to their shoddy workmanship than out skill :)
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