My African violet bloomed once and has never produced flowers again.
African violets need good bright light to flower. This may be difficult to find indoors in the winter. Move your plants to a southern window for the winter. Or supplement sunlight with artificial lights. Only use African violet or flowering plant fertilizers and only fertilize actively growing plants. These fertilizers have the right mix of nutrients to encourage flowering. African violets flower best when grown in the proper size pot. Growing a small plant in a large pot results in lots of root growth and little if any flowering. Once blooming, remove the faded flowers to encourage continued bloom.