Does a lease renewal in PA require some form of new documentation or signatures?

You need to determine if there was any language in the original lease that speaks to this issue. I suggest contacting an attorney to discuss this in more detail.

It's possible. It all depends on what your lease says and what your email says. It's definitely possible.

It all depends upon what the lease states is sufficient form of renewal. Very often it just states that it must be in writing and a court could interpret an email as "a writing"...However, if it states that it must be a writing signed by both parties then an email would not be considered sufficient. It is best to consult with a Real Estate Attorney who handles landlord/tenant matters.