Mmm I would be tempted to suck it up and leave it be...she's probably close to 1 nap but if you can keep 2 for a bit longer with a slightly shorter night overall you may be better off...
Otherwise you have a few things you could try - bare I'm mind it could go either way though!
- 1) push am nap out a touch ie 15 mins and hope WU follows. You would need to shift your day if you do this though.
- 2) cap pm nap to 30 mins, try BT at same time or a touch earlier and see if she adds on that sleep overnight.
I wouldn't personally cap the am nap as this will become your 1 nap soon