Re-auditioning is simply illegal. Once you have got your orchestra job by an audition you have made it.
Every musician has to keep his artistic standard individually. 133 German orchestras, amongst them the famous Berlin Philharmonic, the Munich Philharmonic and others, have unlimited, longterm contracts. Only by building longterm relations – without re-auditioning – high perfomance teams in the orchestra can grow and develop. Re-auditioning is not the way to raise artistic standards. They are forbidden.
My recommendation to all musicians: just boycot any illegal re-auditioning procedures.