Not Feeding

I'm not too worried about this but my emp has not been eating of late.
I've seen other topics on this that say they will "fast" from time to time.
Question is, when should I start putting prey items back in again? She
not appear to be pre-molt and looks pretty healthy.
 

This is exactly what's happening to me right now, it's perfectly fine, they can go for over a month without eating. It might be in pre-molt mode and if so it will get fatter in about 3 weeks or so and you'll know.

Try to offer it food once a week and see what happens. If it just stays in it's hide and never comes out (even at night) and never eats for longer than 2 weeks, there is a good chance it's about to molt.

It's been a while since she fed last so I'll just keep
an eye on her for now. She's just holed up in her
burrow. Pet holes; who'd a thunk it?

Both of mine are doing that right now. Mine tend to go through alternating periods of fast and feast. It's amusing, but I have to control their food intake at times. Sounds like you've made her quite comfortable.

If you are really worried then try feeding a new food, works for all my pets, if it still wont eat then just wait a week and try again.

I have some little scorps (not emps, though) that survived and molted from 2i to 3i for without eating anything for 2 months. A week or so off-feed should not worry any of you.