South american way: I pull two rust free iron bars and wiper rubber profile from new blades, and install them in old ones. Since 2004 this is my way.
Regards
You can just buy universal refills and do that, or pull them out of nicer blades, but it's not ideal.
Sooner or later you end up with fatigue in there, and the tension bars can slip. It's not worth the risk on a vehicle with a bonded windshield, in my opinion.
I've got a nice arc carved across the majority of my windshield because of that, and there's nothing I can do about it, either. I refilled the blades with better stuff for quite some time, but when it came time to replace the frames to prevent failure, the new units (Genuine, but no telling who made it) just fatigued early.
One of those bars slipped out, and that was that. I'll be staring at that arc until something finally breaks that windshield, but it seems those heating elements make it nearly indestructible under normal impacts.
I should really buy one if they're still available brand spanking new, just in case it does break eventually. I can tell when someone else made a windshield, no question. You can spot that manufacturer a mile away, and the subtle warm, slightly green tint Land Rover uses isn't replicated anywhere else. I'd hate to have to go aftermarket.
Cheers,
Kennith