Can't locate my old passport with previous visas.

I am told by my travel agent that to have a new visa issued I will need to provide my old passport with the visa I had to enter China in May or June 2005. I have had a major home renovation in the past 12 months and, so far, cannot locate the old passport.
Is it absolutely essential that the old visa/passport be submitted with the new one and the relevant documents?
Cheers,
Peter