Is there a reason to have a liver biopsy done multiple times?

Many liver biopsies: It depends on the context (diagnoiss, treatment, management). It depends on the definition of many. One measurement (of just about anything) does not give you a trend...And, at times, that is necessary post-transplant there may be a need for many biopsies...

Yes: There can be many reasons to have multiple biopsies. The most common would be to assess for change in chronic liver disease.