it looks to me from the UK CAA , serbia only follows the EASA framework and there exemption for conversions ran out , so it will be an ICAO conversion 14 exams and the rest.....
Serbia and Turkey are former JAA Member States that were recommended for mutual recognition in respect of JAR-FCL before the end of June 2009 by the JAA. These two States are not yet EASA Member States (either by membership of the EU or by formal agreement with the EU) and so their JAR-FCL licences are not deemed to be Part-FCL licences under the regulation. The JAR-FCL licences issued by these two States were previously rendered valid by UK national legislation and so were valid licences for the flight crew of aircraft registered in the UK. This validation under national law could not remain in place with the implementation of the European Aircrew Regulation. Consequently, the previous UK recognition of JAR-FCL licences and related authorisations issued by Serbia and Turkey ceased on 16 September 2012.