If the kid laughs almost uncontrollably at your slightest sound or facial gesture, don't try and figure out why you're so damn funny. You're not (any funnier than you were yesterday).
If it's within an hour of the kid's regular nap- or bedtime, what you're probably getting is the infant equivalent of slaphappy. Don't be seduced by the adoring audience; she's barely holding it together, and she should've been asleep already.
Then once she's asleep, you have time to work on your new material.