most obvious: keep your bike inside overnight.
or, of course: put a brake on your next set of bars if you can suck up the loss in street cred.
there's also: make a sacrifice and run a cheapo stem and bars so if/when they do get stolen again, you won't be that upset.
i've never tried the glue & BB for my threaded stems, but i was definitely considering it before i put a brake back on.