Here's what the sleep experts recommend:

Sleep Schedule

Check their recommended sleep schedule via the Kulala app to ensure they’re getting the right amount of sleep for their age. Adjust as needed.

Movement

Many babies benefit from movement prior to their naps. Take baby out for a walk in a stroller during nap time or use a baby swing to help them sleep longer. The key to these methods and many others is consistency. Over time your baby will associate the stroller or swing at this time of day with sleep, and will begin to sleep longer.

Is this a one-off?

If your baby doesn't sleep for the entire duration of their nap, and this is a one-off, don't change anything about the rest of the schedule. If they're very cranky, it's ok to put them down up to 30 minutes earlier for their next nap. However, the duration of the next nap should not be prolonged, and subsequent naps or bedtime should happen as closely to the original schedule as possible.

Have they outgrown it?

If baby consistently doesn't want to sleep for the allotted duration of a given nap, it's possible they've outgrown it. Some babies simply need less sleep than others. Take note of the naps that are shorter than others, and adjust baby's schedule to feature shorter naps, evenly spaced out throughout the day (except for young babies in the morning–the first nap babies take is often quite soon after they wake up).