If one of your students is kicked out of your Google Meet and cannot rejoin you can try the following steps in order:
In the top right of your Meet click on the “Show everyone” button and then click “Add person”. Add the student that was dropped from the Meet.
You can find more information on adding people in Google's documentation here.
We are recommending that teachers generate a new Google Meet link on their Classroom page every morning.You can check out our page on Classroom Best Practices.