Silly little fixes?

I have always used ACF50 on my trailer connections, both on the pins and wires at the rear. More of a preventative measure (stops corrosion and oxidisation) than a contact enhancement. I've never had one fail or require replacement. Its possibly a little expensive just for your connection, but I use it on my motorcycles / cycles as well, it's very well known in the biker world.

You could get repair kits for heated elements, but a lot depends upon how it's constructed. If it's "printed on the glass" it should be possible to use a kit, a sort of conductive paint, to reapply / bridge the gap. If it's an element within the glass I guess you can fix this, replacement only. 
I've never looked how it's constructed on the Jimny, so that's going to play a big part. The product was available back in the 90s, again not looked if it's still available. Interested in what you find, several of mine don't work, just assumed it's a Jimny thing and have never attempted to correct.

Just googled "heated window repair kit" and you can still get the paint. So it's still an option but looks like it needs a bit of googling to see if it's any good. 

I generally use silicone grease both in the back of the socket and on the contacts. Silicone grease repels water really well. I use it on pretty much any connector that is going to be exposed to water.

So you made me look at mine.
its a "printed on glass" element which means the conductive paint repair system will work.
I also found this.

I don't have a Flir imagine system, but the next time it steams up I'll take a picture for reference. I had a quick look unassisted and I can actually see the break in one of my elements. The others I suspect it may be easier to spot with some form of magnification, my eyes aren't the best anymore.
I may have a go myself in the summer, if you get yours fixed before or find a better way let me know. I suppose a replacement window is an option, but is this a common thing on the Jimny?
Everyone else's all working or is it just me and Lambert?

Broken or damaged rear screen heater traces are quite common on pretty much all makes & models.

There's a quick & easy way to locate the break, you just a voltmeter and a scrap of aluminium foil.