Is there any fee for entry/re-entry on the list of professional representatives?

No fee is payable. Once you have been entered/re-entered on the list, however, membership of the Institute of Professional Representatives before the EPO (epi) is mandatory (Article 5 of the Regulation on the establishment of an institute of professional representatives before the European Patent Office) and an annual subscription is payable (Article 134a EPC). For more information, see the epi website.