The phrase "knew again" typically implies a sense of familiarity or recognition of something that was previously known or experienced. There are many synonyms that can be used to convey this meaning, depending on the context of the sentence. Some possible alternatives include "remembered," "recognized," "recollected," "recalled," "reminded," "revisited," "rediscovered," "relearned," "refreshed," and "reacquainted." Using these synonyms can add variety and depth to your writing, as well as helping you to avoid repetitive language. By carefully choosing the right synonym for each situation, you can effectively convey the sense of familiarity and recognition that "knew again" is typically used to express.