Recently, I've been exploring in my practice the concept of cyclical or self-perpetuating lines, namely musical lines that resolve to themselves. Here is one exercise that illustrates this idea:
This type of practice is more technically oriented and less what I would call "jazz practice". Simply playing the exercise will not teach you much about jazz, but it does incorporate jazz language, so I decided to include this here rather than under "technique". If you do wish to get more out of it than just technique (which is not bad by itself) I recommended learning the exercise in all keys by ear/memory. Here I wrote down the line in all 12 keys, but personally I prefer getting the line under my fingers in one key and then transposing it to all other keys in my head. However, it took me a while to be able to do this, so it's perfectly fine if you play this off the page.
The "self-perpetuating" part in this exercise is marked by a repeat sign. The real challenge is to play it as many times as you can without messing up. You can start slowly and gradually speed up, but what I look for here is consistency more than speed. If you can play the line over and over again with confidence then you own it. Once you can do that in one key, proceed to the next and so fourth.