A different perspective.
I am a buyer of art. Photos, graphic prints, embellished graphic prints, original paintings, and sculptures.
Scarcity of an item does impact its value in terms of the marketplace, but also for the purchaser (it's nice to know you have either the only one or one of just a few). Not everyone feels that way, but if buyers of art are honest then anyone beyond a poster has some ego factor involved (and that's not a negative).
So I pay a certain price for a photo, or a graphic print - I pay more for an embellished version (which realistically is unique because no two embellishments will be identical). I pay more if these are limited editions (and the degree of limit affects that, too). I pay more for original works and the most for unique original works (non-unique original works include, for example, my two Nanimal sculptures that just turned up - they are hand produced but based on an original moulding but limited editions - in a way, they're a little like embellished works but higher on the chain).
So, re-numbering? I wouldn't do it. It affects the provenance of the work (because it may call into question the different numbering of two pieces which otherwise appear to be the same) and that tends to devalue all of them. What I would consider is making a new edition, much more limited, that is valuably different in some way. Perhaps a higher quality substrate or some embellishment. That provides you with a higher value item if you believe there is a market for it without muddying the waters for the already sold pieces.
If I were a collector of your work and had the lesser value item, I may be tempted to "upgrade" or simply add the higher value one, too. Once people have 3 or more of an artist/photographer, it's reasonable to say they're collecting it and as a seller you can leverage that to encourage them to grow that collection (rather than venture somewhere else).