**Analyze** what you do.

Write it down. What tempos are you used to? What rhythmic patterns do you use the most?
Do you tend to repeat the **same intervals**?

Take those melodies that made you feel repetitive. Why are they similar?

You will find out exactly what your **clichés** are. They probably come from your **influences**. These similar lines come out of you musical mind naturally as you **improvise** melodies. You obey that musical instincts as a set of **rules**. This is key.

What you can do:

 1. Once you find out your *rules*, break them. Do you use a lot of *ascending 3rds*? Try a *descending 6th* for a change. Do you use a short-short-long rhythmic pattern too much? Try *long-long-short-long-short*.
 2. Don't just improvise. Write your material. Think of the melody as an entity not entirely dependent of your musical vocabulary. Music can always use some math.

Just remember to let your ears be the judge.