Hello Cherie, I have had an antique mirror "resilvered" and it was
pricey. If all else fails, what about backing the mirror with
another piece of glass--in the form of a "first surface" mirror?
This is thin glass with the reflective surface on the front, not
behind the glass. They are widely used in better kaliedescopes, and
can be purchased at stained glass supply places, as well as
scientific supply places, I think.