For the non-scientific assumption, I've re-pitched many times and I've saved it for a couple weeks and pitched it with good results. I usually run a flame around the mouth of the carboy to kill anything that may be there and then just dump it into a sanitized growler.
After a couple weeks, I've "woken" it up with some wort and pitched it. But that's by dumping off the clear beer that has gathered on top and adding a cup or two of chilled wort from the boil that was going that day and then pitched a few hours later.
After a month or so, I've put it on a stir plate and started it up again like I would from a vial.