Hi, vandas. Congratulations on a wonderful plant. There's no way to guess how long before it would set a new spike. It depends on the condition of the plant, and also it's ancestry and the time of year.
I've had some that start new spikes almost the minute the old one is cut off, and others that didn't spike again for more than a year. I never saw any lawfulness in it-- except that the bigger healthier ones seem to spike sooner. But more or less up to the plant's own whimsy or heredity.
If you concentrate on providing good conditions for growth, it will bloom as much and as often as it can. That's my theory
Brooke, aren't you one who has a violacea alba?