My spider got out once. Found him 3 rooms away wrapped up around the aquarium plumbing.

Look EVERYWHERE. Small dark nooks. Inside shoes. etc etc

There are a few other tricks that I have seen round the net.
If he is small enough to fit, try putting a mouse in a 2 liter bottle and strategically place it.
You can put those plastic shopping bags in different corner/along walls/in doorways and listen for him to slither over one.
Some folks suggest lines of flour in strategic locations, when he disturbs it you will get an idea of where he has been and where he might be headed to.