Gone for a month? Wow...not sure how much help we can be. Can you give us some more info to go on? How big/old was she when she escaped? How did she escape? What kind of room was she in when she escaped? Is it a dedicated herp room? Or a bedroom? Living room? Apartment or house? How sealed off is the room?
Some tips that I usually give to folks looking for a lost snake:
1. Never dismiss small containers, tight spaces or tiny openings...they can squeeze themselves through and into astonishingly small spaces.
2. If you think the snake is still active somewhere inside the house/building/room...try laying a dusting of flour all along the edges of the walls and across doorways at night before you go to bed. Look for tracks made in the night.
3. In whatever room you think the snake might most likely be in, find a quiet activity to engage in and sit silently, listening. (ie: reading a book) This works best in the late evening or early morning when the snake is most likely to be active. You can put plastic grocery bags along the walls, and behind/under furniture to help increase the likelihood of rustling noises to key in on.
I've heard many stories of snakes showing up after being missing for weeks, and sometimes months (and once, even years!). Good luck.