You should not need to scan again, and that won’t work as you are already connected. It is like trying to call yourself from a phone. 
You should not need to change the IP address once you have successfully connected (proof, you ran this job). You should be able to simply right-click the ‘Devices’ button to reconnect.
When you say, “I came back to use my laser, my computer couldn’t talk to it.”, tell us exactly the steps taken to determine this. Did you try to move the laser head around and get no response? Did you try to send a project and get a failure of some sort? Need a little more detail to understand the potential issues here.
We recently refined our communications channel, releasing it when not in use, so you may be observing this. Try the ‘Right-click’ trick and let us know how you progress.
Edit: I just found this good troubleshooting post Oz just posted that is worth review.