African Violets have some specific care details to optimize growth and blooming.
This link will help you.
Try increasing the light. Keep the violets about 12" from the bright window or 12" from a grow light.
12 hours of light a day under a grow light can stimulate flowering.
If the violet is not getting enough light, the leaves will grow upward.
You must use a Violet fertilizer. Follow application directions on the package.
Good root system, means healthy plant. Use a good quality and well draining potting soil.
Humidity levels at 40% are optimum.
Keep the plant from any air conditioning or heat vents.
Sometimes a violet will just 'become vegetative'. Try tapping the bottom of the pot on a table--waking up the plant by adding a bit of stress.
Repotting can sometimes have a stress effect, that may wake up the plant.
Make sure the roots do not dry out!
There are cases that an African Violet will not bloom. Don't take it personal!