How do I reactive an existing employee without adding new? Or do I have to add employee again?

Hi Kathy, 

Making an employee active again can be quite the task especially if it's your first time doing it. Don't worry, you'll be an expert at doing that after following the steps below.

Here are the steps to making an employee active again: 

1.     Select the Gear icon below Add an employee.
2.     Select Include inactive.
3.     Select Make active. 

I encourage you to check out this helpful article for more info on adding, editing and reactivating employees.