If a person has a mistrial in a criminal case... is it possible for the prosecuters to present new evidence in the retrial?

Yes, they can present different evidence.  They don't have to present the same trial over and over again.  In fact, many times they don't present all of their evidence in a trial, it is up to the prosecutor to decide what evidence he needs to convict.  That being said, if that evidence was new and never turned over you have an issue.  That is to say if the evidence materialized and your attorney never had a chance to look at it or investigate it, you have an issue.