I've been reusing yeast for the last 2-3 years.
I sanitize a mason jar, fill it with yeast from the carboy and put it in the fridge for the next batch.
I used to pour off the beer that would rise to the top of the mason jar and replace it with distilled water. Then shake the jar to mix the water into the yeast. My thought was to reduce the amount of alcohol in the solution.
However, recently I've learned that that is not necessary and likely harmfull for the yeast.