When you are missing model output in your archive there is most of the time no need to rerun the simulation but only the post processing.
1) First check if the original model output is still there.
If the output is still there you will find it under the directory specified in ${CLIMAT_outrep}:
${CLIMAT_outrep}/${GEM_exp}/cfg_0000/firststep_*/???-???/*
resp.:
${CLIMAT_outrep}/${GEM_exp}/cfg_0000/laststep_*/???-???/*