Oh:
I tend to play more on the side of "following the PCs' interests", so, as a result, I haven't used the Threats/Fronts rules very much (I would like to do so more!). This means that sometimes I forget about them.
If you're getting a lot of mileage out of your Threats/Fronts, that would be a more "by the book" approach. Look at your countdown clocks, and the unresolved Threats, and consider which it would interesting to bring to bear in full. Ideally, you could get them all into action, so as to resolve these outstanding bits and pieces.
However, you may have too many of them to tackle in this way, or, perhaps, a few have fallen by the wayside. As a general rule, you're not going to want to introduce anything new at this stage: you're looking to wrap up existing story threads and to resolve existing conflicts. That's what will give the game a feeling of reaching a climax and coming to an endpoint.
You may look at your Threats, then, and, most likely, scratch out those which don't seem most relevant and most interesting. Focus on 1-3 Threats which are intimately interesting to everyone and feel like they really need resolution; drop everything else. Push those hard!
I think the ideal approach here would be somewhere in-between these two: you want to follow your Threats through, but also keep an eye on what the players and characters are interested in and always push towards there.