In Tracy's last book, she advices how to go from 2 naps to 1 ...
By making the morning nap progressively later, yo can eventually make it disappear. The suggested timetable below assumes that your child is at least 12 months old and normally naps at 9.30am. Times may vary, depending on your child, but the principles of gradual transition remain the same.
Days 1-3: Put her down 15-30 minutes later for her morning nap - 9.45 or 10.
Days 4-6: If possible, put her down 30 minutes later, so that she's going down at 10.30. Give her a snack at around 9 or 9.30. She'll sleep for 2 or 2 1/2 hours and have lunch around 1.
Days 7 - however long it takes: Every 3 days, make the nap later and later. She might have a morning snack at around 10 or 10.30, go down at 11.30, and wake for his lunch at around 2. You might have a few rough afternoons.
The goal: Eventually she'll be able to stay up until non, have his lunch, play a bit, and then take one long afternoon nap. She might have some days when she just can't make it without a short morning nap. Go with the flow, but don't allow her to sleep for more than an hour.
Hope this helps, let us know how you get on.
Rachel xx