After a year, you can lead the way and actively eliminate nursing sessions- generally, as long as your LO is eating a decent solid food diet and is nursing 3-5 times a day her nutritional needs are being met. Or you can let the baby lead the way, in which case the demand level will still go down as the baby naturally and gradually transitions to a majority solid food diet and becomes less and less interested in nursing. I prefer the latter approach because it's easier, but it can be a lot slower than the mother-led approach. For example, my first LO was still nursing around 10-12 times per day at a year old, and she didn't go down to 3-5 sessions per day until after she turned 2. (She really, really loved "pupple.")
As for the "again? didn't you just feed her?" folks- just go :eyebrow and ask "would you rather listen to her cry? And why are you so interested in what I do with my breasts?"