Thanks for posting your question on Justanswer.com, a global paid independent support site.My Name is ***** ***** I will be assisting you today.As you have replaced the router, you have to reconnect the printer to the new router once more then, you have to reinstall the printer on your PC and Mac and reconfigure the printer settings on the Ipad.
But, you said this " If I go to the printer in "Devices and Printers" and click on HP AIO Wireless Printer Remote I get an error that says contact the system administrator about re-installing the app. " ?
Sorry, I do not understand your reply, once you are saying that, you are getting a error message on the PC and then, you are saying that you can print from the PC if you do not cooperate with me and give me the information then, how will I help you ? This type of problems can be fixed very easily only if you give me the proper information and there is no shortcut for this process, I will need some information before I can help you.