Do you mean rejuvenate the cable? Try and restore that section of the cable? I'm going to attempt some silicon spray and soften the rubber. My theory is to lay out some glad wrap long enough to wrap above the Y-spilt then spray a generous amount of silicon spray on the cable and wrap it so oxygen cannot get in (so it cannot dry out) then let it sit for 24-48 hours, maybe repeat again.
We're not even sure it is oil from our skin causing the issue, it's rather bizarre how it occurs on both sides exactly in the same section.
If the silicon spray works I will create a thread and tutorial with photo's for others. There are other treatments, some recommended soaking the rubber in WD40 or brake fluid however I do not suggest this as the cable will only soak in the lubricants then rub off onto your skin.
I've kind of set a mission to try and heal the cable before it gets past a restorable point.