My three year old daughter has stopped taking her afternoon nap. How do I get her back to the routine?

I guess, if you will also sleep by her side it will help. Make an atmosphere. First feed her well, so that she doesn't ask for feed soon after you have winded up everything. Then take her to her sleeping room, close the curtains, and yourself pretend to be sleeping, she might still play on the bed for a while but seeing you sleeping, she will eventually doze off. It works with my daughter, hope work for you as well.