Do peace lilies need to be root bound? I have been thinking about moving my peace lily to a bigger pot, is this a good idea?

A peace lily will definitely flower better if it is root bound. If you do move it to a bigger pot, make sure it is no more than 10mm bigger in diameter than the previous pot. Move the whole plant and soil into the bigger pot and then put new potting mix around it. Often peace lilies don’t like to be in a pot that is too big because they become waterlogged when watered.