Always provide fresh food, it doesnt matter if your bird eats it or not. Simply allowing access to the food will eventually get your bird to eat it and like it. I had a picky lovebird a while back who only ate seeds. I immediately switched her from seeds to sprouted seeds. She took to that quickly and then I offered her fresh food but she would not eat it. Chop up fresh food, various colors and shapes, and then put some millet in it and mix it. Your bird will dig through the fresh food for the seed and will likely get a taste of this or that. Eventually s/he will get used to the tastes and actually eat them. It takes a while though. I also would put fresh collared greens or carrots or other snipping in various places around the cage. My lovebird would pretend not to care but when my back was turned she would investigate these 'new' things and try them. Your bird may not like the taste immediately but will get used to it and eat it. Is your bird tame? My lovebird wasnt tame so It was harder to introduce her to these foods. With tame birds most of the time you just bring the new food up to your mouth, pretend eat it while making exaggerated yummy noises, and your bird will likely want some and take a bite of it when you offer it. This is how I introduce new foods to my conure.
Good Luck!