Judging by the photo and experience with lilies in my pond, they look to have lost all the compost and need re potting with a decent pond lily compost. You also need to make sure that the container is big enough.

Most lilies appear to be sold like ordinary plants - with the minimum pot size. When I bought my lilies, the retailer openly suggested that I re pot them straight away.

Some people advocate re potting every spring to get the best display.

All the best with them.

Chris