Stats & rates.

[Momof4]

I also charge more for part-time than full-time. In my case it's $3 more per day. The reasoning is that they can schedule around stat days and I can't fill the empty days so I lose out when I take a part-time family.

I agree that I wouldn't raise your rates more than $1-2 per day for current clients. Especially if you have a lot of competition around you. You still have to run your business as you see fit, let the clients know that, but you have to be fair.