Seal the room so it can't escape. I had a T. gigas sling escape and go into the walls, found her 3-4 days later. Unfortunately, seeing as she is arboreal, where I found her is sorta irrelevant (on the ceiling).

I would keep a close eye on every corner in the room, most small animals travel along the walls rather than the middle of the floor. You might even want to set boxes or totes in all four corners of the room and check behind them often.

And do what Jeff said, unless you saw it escape, there is a chance it's hidden in the enclosure.

Good luck, I hope you find the little guy.