Employment Law Questions? Ask an Employment Lawyer.
Hello and welcome. I am truly sorry to hear about all this.
Unfortunately, though, there is nothing illegal about firing and then rehiring someone. As a general matter, employment in the state of WA is purely "at will" absent an express agreement to the contrary. At will employment can be terminated for any reason not amounting to discrimination on the basis of a legally protected trait (race, religion, gender, etc.) or retaliation for engaging in certain forms of legally protected conduct (filing a wage claim, taking FMLA leave, etc.). It doesn't matter whether the basis for termination is fair, reasonable or even true. So, the relationship can be terminated and recommenced at any time for just about any reason.
You can certainly refuse to undergo all the new hire requirements being imposed upon you for the second time. However, your employer is not legally required to employ you if you refuse. So, while it's quite unfortunate and understandably frustrating, you have to decide whether you want to do what your employer is asking or seek alternative employment somewhere else. I am truly sorry.
If I can clarify anything at all for you, please do not hesitate to ask. It is my pleasure to assist you further if necessary....