ok i will try putting it in another hot soak. maybe another 3 hours this time?
I've found its more about temperature than time, in general. Anywhere from 45 minutes to 1:15 should be fine. Too, agitation will sometimes help the fibers to tighten up even more. I'd suggest the hottest wash setting on your machine-wash possible, on super gentle/delicate. Then they're sitting in a sauna with the top closed, getting shaken up every couple of seconds. It's brought out the most shrinkage in old 501 STF that I've experimented with.
The above answer works too. Get them soaked in a really hot bucket or something, and throw them in the dryer on high - although they will soften up and you'll usually lose that "raw denim" feel and texture.
Either way, depending on what you want.