Napping schedule

How do you get your toddler to go from 2 naps to 1 nap? My daughter is 15 months old and takes 2 45-minute naps per day. Our pediatrician said that around this age, kids will start napping once and should be napping 2 hours per day. She said I could try keeping her up longer in the morning, feeding her a big lunch and then putting her down right after lunch, around noon. I have been trying that the last few days with little success so far. I'm not stressed out about it but I would like her to start taking 1 longer nap. How did you get your toddler to go to 1 nap?