Lovies can be very picky about food! If you're having trouble getting your bird to eat enough fruits or vegetables, you may want to try chopping them up into much smaller pieces and putting the slices into the seed dish. My lovies are wary of whole vegetables but will scarf down the chopped version.
Do you have pellets in the cage? I would advise keeping a large supply of pellets and fresh food and a small amount of seeds available to eat.