I'd let her sleep. Although, it depends how long does she sleep for overnight? If she's still only have short sleeps and waking through the night, just change her when she next wakes up.

When DS was a newborn, I'd just let him sleep through in whatever he was in as I knew he'd wake up a couple hours later. Now as he sleeps through the night from 7pm to 7am...if he falls asleep and he's not in his PJ's or needs a nappy change, I'll change him. Sometimes he stays asleep while I change him!