Offhand I can think of two times that I recall She-Ra changing back into Adora. One happened on accident in "The Stone in the Sword." - The jewel cracked and she reverted back to Adora. The other time was in one of the episodes with Sea Hawk. I'm not sure if I'm remembering this right, but I believe She-Ra goes "off-screen" and we see a bunch of flashes and then she comes out as Adora. She didn't say anything though. I hope I got that right.