Ow Nic we've got the same thing happening here, Vicky's waking up between 12 & 1am then Alex is stirring around 3am and then DP alarms goes off at 4am and i have to get up by 5am in case Alex gets up and trashes the house. All i can think of is
1. Is she warm enough as its getting rather crisp around here in the early hours of the morning.
2. Is she starting to teethe? Maybe try one of the more natural remedies which might help her sleep a bit more.
3. Do you still wrap her - we are still having to wrap Vicky (under the arms) or she just keeps waking?

Apparently if you read other threads is does improve but i know that doesn't help right now. Maybe get someone over to watch the kids for a hour or so in the arvo so you at least can get a nap? If you lived nearby i'd do it for you.
Hope you get some zzz's today