sleeping question?

Mom • My name is Raschel. I`m married and have a wonderful 4 year old son and a beautiful rainbow baby girl born nov 2016.
How long do you let your babies nap before you wake them? My almost 4 month old has been napping for almost 5 hrs. She's been asleep since 1:30 and it's going on 6 and she usually goes to bed around 7:30. Wondering if this will make her stay up later? Thanks!