I actually like my boots soft and broken down - I'm not really jumping much, and for low level ice dance, as long as they don't fold over, and I can still control the blades by aligning my ankle, stiffness isn't a problem. I don't want to reduce my range of motion in any way, just slow down the sideways bending a bit. So I continue to use broken down boots.
A manufacturer rebuild (at least from Klingbeil), as I understand it, consists of ripping apart the upper part of the boot at its seams, completely replacing the stuff in between the inner and outer leather layers as far down as they can easily reach, including pretty much everything that gives boots their stiffness, and re-sewing the seams. So if a loss of stiffness, and/or maybe the formation of a crease that would be fixed by stiffening is the problem, a rebuild is an excellent long term solution. But they only rebuild the top of the boot, down to a little below where breakdown creases usually form. They don't modify the lower part of the boot - such as the toe box, or near the insole, or the part of the boot significantly beyond the front of your leg, because it would be too much work.
So, look at what is breaking down. If the seams are falling apart, it is a lost cause. If the problem is the lower part of the boots, it is a lost cause. (Exception: if the heel is starting to detach, that is separately fixable, and doesn't need a rebuild. Likewise, insoles are easily replaced.) But otherwise, if stiffening the upper part of the boot (such as where the "breakdown crease" usually forms) would fix all problems, a full manufacturer rebuild should be almost like a new pair of boots. They may not look new - but they will feel new, and should last nearly as long.
(However - if all your shoe store wants to do is to glue in a stiffening layer inside the boots, without tearing apart the seams and replacing the insides - that probably won't do as much. And if they aren't careful to "feather" (thin to nothingness) the edges of that layer, so you have an abrupt edge at the edges of that layer, it will be very uncomfortable._
All modern upper level figure skating boots (by which I mean boots that have an inner leather layer for comfort, an outer leather layer for looks and lacing, and one or more super-stiff layers of something in between that are the heart and sole of the boot), are much stiffer than any other type of shoe I know of (except downhill ski boots). So I'm not sure an ordinary shoe store would know what to use to replace the insides with that is stiff enough to do the job, especially if you ever jump. Unless they've worked on upper level skates before. Also, what they use might not be heat mold-able.
To ponder: Many serious skaters spend a lot more money on lessons, driving, ice time, blades(including sharpening), tests and comps than on boots. Maybe new boots are worth it, if they make you happier?