Hey Dan, It is so hard to know isn't it? I would take Livvy's cue, if she seems like she still needs it I would give it to her. If you think she is sleeping too long, maybe go stomp around near her door after a good time - say 2 hours, turn the vacuum on etc so that she wakes naturally without you physically being in there IYKWIM!?? That's what I occasionally do with Izzy.
She is still on 2 a day and sleeps for pretty much 1 1/2 -2 hours at both sleeps and doesn't really fuss when I put her down so I know she isn't ready to cut it out yet.
Good luck with it! Can you believe our little babies are nearly one!