I repitch slurry. I don't transfer hops or much break material to my fermenter so I just dump what is at the bottom of the fermenter, after kegging, to a jar.
I then weight this out for pitching. I use Mr Malty for a baseline on how much yeast I should pitch. It tells me 100ml, I usually measure out 100g because I didn't have a way to measure volume.
I did notice the other day that 1/2 cup is 125ml so I measured a cup of slurry and it was 125g exactly, this will depend on the thickness of the slurry.
This has worked good for me, Just use measuring cups to get your volume to pitch.