Renewing Leases/Raising Rent in Pennsylvania

Hi All - We are in the process of renewing leases/increasing rent for the first time since we've owned rentals. I'm curious how this should be done properly in Pennsylvania?

Do tenants usually sign a new lease every year? or do they need to sign a rent increase letter and return it? OR is it fine just to send a letter indicating that rent will go up without needing a response?

We have it in our lease that it "will renew for the same period of time if unchanged by either party"

Also, does that have to be sent via certified mail? We just want to make sure we do everything right. Thanks!