I downsized at the end of last summer, partly out of curiosity and partly because one of my lobes was irritated after an insect bite. I just left my plugs out for a week, and my lobes shrank from 9/16" to about 8-9mm. No special care, just a daily massage with jojoba or emu oil as I would when wearing jewellery.
I stretched back up to 9/16" over about 6 months, my lobes are smoother, thicker and stretchier for it. Stretching back up wasn't really like stretching, more that my ears were just ready for the next size after about a month. I've just stretched to 5/8", I'm sure the downsizing last year made this stretch very easy
Another nice thing was the variety of jewellery I could wear on the way back up....... I'll be downsizing and restretching again in the future and definitely recommend it!