Can a child retake the second year of GCSEs?

My daughter seemed to be doing relatively well at school, predicted 5 and 6 grades for most subjects. School reports gave her an average score for attention to learning. She has just completed her mocks and she is scoring 2 and 3 for most subjects, and didn't even get a score for science. If she had one or two subjects she was struggling with, she might be able to pull them back but with most of her subjects at the bottom of gradings, it's unlikely she can improve all of them quickly. We are trying to consider options for her, one of them being that she take her second year of GCSEs again. Has anyone had experience of doing this?