A foreigner residing in the Republic of Croatia and a Croatian citizen residing or residing abroad and coming to the Republic of Croatia may, on the basis of a valid foreign driving license issued by the competent authority of a foreign country, subject to reciprocity, drive a motor vehicle on the territory of the Republic of Croatia, and in these cases an international driving license is not required.
You can use the driving licence issued in an EEA Member State for operating a road vehicle as long as it is valid, i.e. until it expires. The driving licence does not have to be replaced with a Croatian one, even if a EEA Member State issued you a driving licence based on a driving licence issued in a third country.
You can use a valid driving licence issued in a third country for operating a road vehicle for up to a year from entering Croatia, after which you have to replace it with a Croatian driving licence. If, at the time of submitting a request for issuing a Croatian driving licence, the driving licence issued in a third country has been expired for more than six months, you cannot replace it for a Croatian driving licence - in that case, you have to take the driving test in Croatia.
You can find more information here:
Replacing a Driving Licence - gov.hr