The moment they received their stuff it underwent a major refit for NVA purposes AFAIK. Meaning for example tools replacement and additions (wheel chocks and rear NOTEK light come to my mind) and electric components (lamps, radios and such stuff according to NVA standards) which included usually repainting as well. Some stuff remained in USSR colors if I remember right, like for example the few MAZ 537 Tank Transporters they had (but I'm not 100% sure here, need to check that again). They also received Polish (licensed T-55 tanks), Czech (Tatras), and Hungarian stuff (Ikarus buses). Same procedure there.
Every few years they had so called "Hauptinstandsetzungen" (Major Maintenance Services) which included repainting if necessary (i.e. when the color was heavily faded).