I brewed one up sunday. No decoction here tho - maybe next time.
You should still have a ton of yeast. Yes, the krausen contains a lot of yeast, but not all of it. You should raise the temp up to 50. If you used the urquell yeast, it is not expected to be active at 44F.
(fyi, I split a 10g batch between the Wyeast Urquell yeast and W34/70 (dry). I'm going to test the same beer with some other yeasts in a couple weeks. Must perfect this recipe!