Typically, three main query reformulation types in sessions are considered: generalization, specication, and drift. We show that given the full context of user interactions, repeat queries represent an important reformulation type which should also be addressed in session retrieval evaluation. We investigate dierent query reformulation patterns in logs from The European Library. Using an automatic classification for query reformulations, we found that the most frequent (and presumably the most important) reformulation pattern corresponds to repeat queries. We aim to nd possible explanations for repeat queries in sessions and try to uncover implications for session retrieval evaluation.