Being on the same wavelength means to understand each other, to have a similar mindset or a shared perspective. If you're using this phrase too often, it's time to mix things up a bit. There are many synonyms you can use to convey the same meaning, such as being in sync, harmonious, on the same page, in agreement, in harmony, and aligned. These words can help you communicate the same idea in a unique way and avoid repetition. It's always a good idea to use a variety of language and expressions to keep your writing or speaking interesting and engaging.