I don't know the answer to your question but, being
curious, I did some lookups on "re-staging".

I found a definition at:
http://www.texaspetimaging.com/timifile/medi2003.html
and found lots of uses of the term in many types of
tests and many types of cancer.

I get the impression that "re-staging" is not the name of
a particular biopsy technique, but rather the intent of the
procedure - i.e., an intent to check on the status ("stage")
of cancer after treatment may have changed things.

You'll have to ask your doctor what he plans to do
differently from ordinary biopsies.  It might mean that
he plans to use the same technique as an ordinary
biopsy, but take the samples from different areas.

On the issue of your actual cancer, the fact that your
PSA has stayed low is wonderful and may indicate that
if you actually have cancer, it's a very low grade non-
growing disease that is an excellent candidate for
watchful waiting.

You might ask your doctor what the "Gleason score"
was for the two "chips" in which cancer was detected.
The lower the number, the better.  Numbers below 7
are good.  Numbers below 6 are very good and may
indicate a very non-aggressive disease.

Good luck.

   Alan