What happens if you just leave her in her cot? If she's happy and just talking/playing with herself she might end up putting herself back to sleep. My DD does this and if she's happy I just leave her and usually 20 mins later she's back asleep. Maybe worth a try?
We do try this. She ends up screaming after about 15 minutes of happily chatting. That's usually how we get her to sleep for her day sleeps. She was fine for about 15 minutes just before, then started screaming - so I went in there and patted her bum - she was asleep within 3 minutes.

If she's happy we leave her. If she's screaming, we tend to her.