This is a simple idea that will help you play with clarity.
You improvise an idea over two bars of Gm7 and then transpose the idea to Bb minor
Play the same idea exactly in the new key.
It forces you to start and end an idea within a time-frame of two bars.
If you find yourself going over the bar length then work on making sure you can hear/think/feel what two bars is.
Also, there’s the challenge of playing something memorable enough to remember what you just played in order to play it again! Plus the added challenge of now having to play that idea in a new key.
Take the last thing you play at the end of the fourth bar and use it to start a new idea.
Take the last thing you play at the end of bar two and use that to play a new idea in the new key. (so there will be no repeating of the first idea).
Try to never repeat an idea. Maybe you could try to make all the ideas unrelated. (a weird way of working on making your ideas more related), or maybe try to catch yourself when you feel yourself travelling down a familiar path and change direction. (tripping yourself up, if you like)
The basic exercise is seemingly simple, but TRY it! It’s not as easy as you think.