The phrase "then again" is often used to express a contrast or to introduce an alternative viewpoint to a previous statement. However, there are plenty of other phrases and expressions that can be used in its place. "On the other hand" is a great option to use when presenting an alternative viewpoint, while "alternatively" could be used to introduce a different or opposing idea. "Conversely" is another option that could be used to bring in a contrasting point. Other phrases include "in contrast", "nevertheless" and "despite this". By using a variety of different synonyms for "then again", writers can keep their writing lively and engaging for their readers.