Sometimes they can drop right up tlll they are about fourteen months old. It is not unusual for them to still be retained at about nine or ten months. However if it is retained in the abdomen they can become cancerous, and castration is usually recommended. If it is, castration is not quite so straight forward, because they have to go into the abdomen to remove it, rather than do it from the outside. Then you have to decide which is the greater threat, anaesthetic and operation or the chance of it becoming cancerous in later life. I would give it a month or two then get your vet to advise.