If I remember correctly, after the body of the Ancient One disintegrated, there was another pile of dust and bones laying near the first sorceress' feet. So
~Was that a cell phone!?~

Each season of Beastmaster has the same direction overhaul, retcon and continuity problems that the movies did.
"I said no camels, that's five camels, can't you count?"

Why did they replace the Sorceress in the first place?

I wonder the same. I think they only brought her to replace Monika Schnarre's character in season 2, but when she returned, they didn't bother to mention what happened to her replacement.