Best training program for late-season goal with lower fitness requirements

I have just come off a 5 month training program training 10-14 hours/week.

I would now like to switch to a training regime of 6 hours/week max to keep myself in shape for an event in September. Obviously I will not be able to keep up the same fitness, but I would like to keep it as high as possible within the given time restrictions.

What would be the best program to choose? It seems that all program options will target a higher fitness than your current one (which is not unreasonable).