Just wanted to reply and say that I am in the same boat. I am trying to wean my DD who turns 2 in a couple of weeks. After a failed attempt at night weaning (she was still crying for it for long periods of time in the middle of the night after a month), we switched to cutting it out during the day and only nursing at bedtime and during the night. It's so much tougher this time than it was with my first!
I also wanted to say that you don't necessarily have to "substitute" the breastmilk with anything. I didn't with my older daughter. She only really started drinking cow's milk when she was around 3; she mostly just drank water and I never put anything but water in both of my girls' sippy cups (they will drink milk and occasionally juice in a regular cup at the table). If the child is eating and drinking well, there's no reason to think she needs to be drinking large quantities of milk. With DD#2, I am trying to distract her from nursing when she asks for it by offering her other things to eat and drink, mostly fruits that she likes (dates and pomegranate seeds, which we find in abundance where we live) and lately, chocolate milk. The latter is borne of desperation!
Good luck with everything!
Mom to two little girls (born 6/08 and 2/11) and another on the way.