Still Making Milk

My brother's cat had kittens back in February, and they seem mostly weaned, but the cat is still producing milk. She keeps wandering the house trying to get the kittens to nurse, and it seems painful. Is she going to dry up soon, or do I need to give her something to hasten it along?

Based on the info on one of you older threads they only around 9 weeks so Sooner or later she is going to tell them to back off