If she is open to both levels, block one off for now until she gets used to one level. As she gains courage and familiarity with her surroundings then open up the second level. Give her several places to hide, house, tubes etc. Cover the top with something that she cannot chew and if possible push the cage into the corner (but not completely up against the wall - that way she is only being approached from two sides instead of potentially four.
Good luck - we all hate moving and chins are no different.