Any Tips for Naptime

Any tips to help lengthen naptime? My little one will be 4 months in a week and naps the last 2 weeks have been rough. She sleeps for about 20-30 minutes (sometimes less) then wakes up crying. I'll spend the next 20ish minutes trying to get her back to sleep only for her to wake up as soon as I put her down.

We have a consistent routine but it does not help with sleep. I'm jealous of all you ladies who only had to follow a routine to get your little ones to sleep better.