When you are in stop mode, make sure that you also hit the save button, if you take a longer break. However, every reading taken by a connected laser is also saved on the server immediately.
When pushing the start button again, measurement will continue where you've left off (the first empty field is selected automatically).
When all values are successfully added, make sure to have a look at them if something is odd. You may delete the specific value and re-read it from the laser. The first empty field will automatically be selected when you hit the start-button again.