How about, instead of a choice between nap / no nap, you cut down her nap? I'm not sure how long her nap is, but if she's getting a couple of hours, maybe wake her up after an hour? Suddenly switching to no naps may get her overtired quite quickly, and may mess up the night sleep anyway.
Dropping that last nap can take a good while to get used to, and she is on the young side to be doing it completely. Most children do it between the ages of 2 and 4. When we did it, we gradually cut the size of nap down, over the space of a few weeks, and, then, once it was finally gone (just after he turned 3), I found he still needed 'downtime' in the middle of the day - under a blanket watching tv on the sofa. That gave him a chance to recharge his batteries, and, occasionally if he was really tired, he'd fall asleep.
Hth
, let us know how you get on