Have you tried an earlier nap?
My DD is 2.5 and we are going through rough bedtimes. Regardless of what time, how long the naps are, she will play in her cot until after 8.30pm.
another member, Stacy, has had some success with earlier naps, you could try that, but my DD will not entertain a nap until 12.30pm, sometimes 1.30pm even, so I only let her have an hour on those days. I never let her sleep past 2.30pm.