"It was so quick and easy that I'll never wait so long to do it again"
How I did it: I've had Petey the Peace Lily for about 8 years now. He's been repotted and divided up a few times. First, I evaluate the size of Petey. He usually needs to be divided between 2 pots and since I had two separate Peteys I bought 3 new pots. Then I bought potting soil. I waited for a sunny day and took Petey outside, transferred him from his 2 old pots to the wheelbarrow, and shook him out into 3 equal sized plants. I put some of the older soil in the bottom of each pot, then put each Petey in and held him at about the height he should be (a few inches below the rim of the new pot) and began filling in soil around him until he was secure. Rinse and Repeat. I took extra special care of him for the first few days just to make sure everything went well. He's all sorts of happy in his new pots. And now I can give 1 Petey as a gift :)
Lessons & tips: As soon as you feel that your plants should be transferred and given new soil, just do it. It takes hardly any time or money.