Here's what I've done. I have an escape artist who gets out every now and then (I have NO idea how!).

I'll open the window and cool the room. I leave a heat lamp on in the middle of the room directed right over a hide. I check every 2 hours or so, and presto! They're there every time.

A few warnings though: If you don't find it within a few hours, make sure you bump up the heat on the rest of your collection so they don't get too chilled. Also, if it takes longer than a day, you run the risk of having the escaped bp get sick from the cold.

I've also left rats out to thaw throughout the day and the scent has drawn them out too.