The subconscious mind often uses dreams to motivate us to take certain actions. If we didn't respond to a dream that the subconscious mind sent us then it might keep repeating the same dream over and over until we take actions (See why we dream) .
If a long term problem wasn't solved by a person then his mind is very likely to remind him of it through his dreams. A recurring dream can be the minds way of thinking about a problem that never got solved .
If an old problem resurfaced once again in real life then a recurring dream might happen as a result. Because Dreams reflect what happens to a person during his daily life the resurfacing of an old problem can cause a recurring dream (see why we dream in symbols).
An unresolved psychological concept such as the failure to accept something that already happened can result in a recurring dream. A recurring dream can be a reflection of some beliefs that the person still has trouble dealing with .
If a person kept moving in circles without figuring out how to solve his important life problems then recurring dreams might occur. The recurring dreams in such a case are a direct representation of the fact that the person is moving in circles .
If a person was worried about something for a long period of time then he might see recurring dreams. Those recurring dreams are usually a representation of that persons's worries (See why we dream about people).
Recurring nightmares can happen after a traumatic event. The famous tidal wave dream is usually experienced by people after trauma. The dream represents the helplessness and frustration a person who suffered from trauma is experiencing .
Recurring dreams can be very disturbing and this is exactly what the subconscious mind might be trying to do. By disturbing a person with the same annoying dream the subconscious mind will make sure that this person will start to look for the causes and so fix his life problems .
If a person kept doing an action that goes against his core values then a conflict might arise between his conscious and his subconscious mind. This Conflict can manifest into a recurring dream where the subconscious mind tries to remind the person of his core values .