In Tibetan Buddhism, there is a ritual where monks spend weeks creating mandalas out of sand. Then the artwork is swept away and poured into running water. The point is to remember the impermanence of all things. Dance is like this, no matter how detailed your choreography or how canned your music, each performance will be different.
But dance can be like meditation in another way, if the dancer is able to enter a flow state, they
can escape judgement from their rational brain and fully be in the moment. In Arabic dance, this flow state is called Sultana and is related to Tarab, the ecstacy that can come from being moved by the music. You can learn more about these from Sahra's article on her Journey Through Egypt site.
So, how do we reach this meditative, flow state? You have to be able to not think, so in your movements, drill them so you don't have to think about your technique once you're dancing. When the performance starts you want to leave your movement to muscle memory. To learn not to think of what moves to do next, drill transitions but also trust what you learn from "follow the bouncing butt" lessons. Watch lots of bellydance clips (and dance along), and listen listen listen to Middle Eastern music in order to develop intuitive musicality and movement associations. Learning what you know is helpful to create confidence, and systematically learning helps to speed up the process for those of us who didn't grow up in the culture. But ultimately, you want to improvise and give yourself over to the feeling in the moment so more formalized pedagogy has to be balanced with putting in the time to absorb it all into your bones, to the point beyond consciousness. You also have to, when performing with this goal, be able and willing to detach from judging your moves or artistic choices during the dance. You can always look at film later, but you can't change it in the moment without disrupting the flow anyway, so allow yourself to let it go.
Improvisation is there and then gone, like a sand mandala it can be a meditation on impermanence. When you train things into your muscle memory and instinctive responses by building intuitive associations it is an exercise in turning off your conscious mind it can become a meditation that connects you to your body, senses, and the present moment. Some times, that feels just as good as the internal massage a well done isolation creates.