I'd set up another box similar to the one the hen's in. When you have the new box set up with new nest material, like pine shavings fresh out of the bag, take the hen and give a small spritz of Frontline spray: http://www.revivalanimal.com/Frontline-Spray.html
Do this at the base of the neck where it joins the body, mid back, once under each wing, and once below the vent. Be sure not to spritz any on the vent as it can irritate it. Let her stand in an area for a few minutes. Carefully take each egg and look to see there are no mites on them and place them in the new box of shavings, then put the hen back with her eggs. If you see some mites on the eggs as you remove each one, gently wipe each egg with a soft tissue over the sink before putting it in the new nest. Spray some Frontline in the sink. Take the old box out and spray it down and the with Ravap or Permethrin. Dump the old nest material in a plastic bag and spray the hell out of it. Seal up the bag of old nest material and toss it in the garbage can. Spray the old box again.
