I've been busy writing an article about edge maintenance on a Coticule. It got finished, but it lacked clarity, so I haven't published it. It's a simple topic, but I'm specialized in making things very complicated.
In essence, touching up a and edge that lost a bit of performance, is reaching back into the honing sequence, and bring back the edge from the point it degraded to, all the way up to peak performance again. When done at the first signs of edge deterioration, refinishing is all it takes. But edge deterioration is not a simple process. We deal with a slowly progressing process of rounding the very edge. This is what can be corrected with a refinishing at the earliest signs. But we might also experience tear-out: depending on -at razor level- the steel and the bevel angle, and -at user level- the coarseness of the beard (influenced by prep) and the stress the user puts on the edge by deviating from its ideal cutting angle. Such tear-out of small fragments of the very edge can't be undone by a simple refinishing. If that kind of micro-damage accumulates, the razor reaches a point where it needs rehoning, instead of normal edge maintenance. It depends on razor and the person using it, how many touch-ups will be possible. For those who have a microscope, this accumulation of micro-damage can easily be monitored.
If a refinishing on water doesn't give the desired outcome, you could try reaching a bit further back into the honing sequence, i.e. starting out on a very light slurry and take it from there.
I have about 4 or 5 of my razors home at the moment. They don't get much use, as I mostly shave with razors that aren't mine, but when one my own seems to be lacking during the shave, I simply grab a Coticule and give it 50 laps or so. I haven't honed any of those in over a year, maybe even two years. I have a few others that are usually on loan. I hone these when they come back home.