[troy@uk]

I am going to brew a 5 gal, 1.055 OG lager and need a large starter.  The WL yeast I bought from my LHBS is 3 months old (Best by Dec. 11).  On last Wed (11-3) evening I pitched a 1600 ml starter on a stir plate.  I plan to run that for 48 hrs, crash and decant over 24 hrs, then add another 1600 ml wort to the flask and run for another 48 hrs on the stir plate. Then I plan to crash it again and on Thurs (11-11)(brew day) I will decant, raise to pitching temp (45 F) and pitch into the batch.
  My question is about the crashing in between starters. Is it good to crash in the fridge and then warm up so many times in a week or should I just let it settle at the same temp and decant cloudy wort?

[tygo]

That's a pretty small starter for that beer.  A gallon starter would be closer to what you need for a lager of that gravity.

But to answer your question there's no problem crashing like that between steps.  That's how I make all of my multiple step starters.  By crashing and decanting you'll collect a lot more yeast.  If you just decant after resting at room temperature you'll decant off a bunch.

[hopfenundmalz]

Repeated feeding with the same amount of wort will give you more cells, but the amount you get goes down.  You need to increase the volume.  If you pitch too many cells into the starter, they start to make beer and not propagate.

It would be better to pour off the yeast into a storage container, put that in the fridge, and only put a portion into the new starter.  Crash and then pitch all the yeast (from starter 1 and 2) into the lager wort.  That way you will pitch more cells.

This was covered in "Yeast" by Chris White and Jamil.

I agree that you need a bigger starter.  Use mrmalty.com to calculate the amount.