Put some strategically placed blobs of Shoe Goo on the treads to increase traction. Maybe rough up the spots you plan to put it on with some coarse-ish sandpaper to increase adherence.

This is the first, and very cheap and easy, thing I'd try. I've done this on other shoes when the soles are or get slippery because of wear, and it's grippy enough to help quite a bit. They probably will wear and fall off, so probably will be a 2 minute "maintenance" item you'll have to do every once in a while, rather than a permanent fix.