Lipstick plant is unlikely to bloom if it isn't a bit root-bound...so if you've been moving it to a larger pot every year that could be the problem. In the future, don't move to a bigger pot until the pot is full of roots, with not much soil left.

Also, what is your fertilizing regimen? Lipstick plants should be fed with a food for blooming plants...African Violet food is perfect as they're in the same plant family, gesneriads. But don't over-do the fertilizing, dilute to half the dose recommended on package.

Karamy

You probably won't see blooms until late summer/early fall which is when lipstick plants usually bloom.