Can I Re-Terminate HDMI cable?

Only if you avoid typical amateur mistakes.
In that case no time estimate is available.

Those DIY HDMI termination kits will degrade the signal because you are using screw clamp based terminations.  Also, you won't have as good of "strain relief" on the cable itself.  My opinion is that it's not worth it.  Just spend another $100-200 on a good new/used HDMI cable.

Also, there are going to be timing issues if you trim the wires at different lengths.  Shielding is lost as well on this termination.

Thanks guys. I had no plans to DIY. I was thinking of sending it to Harmonic Tech and having them do it, or some other reputable company or person. I probably should just buy at least one slightly high end HDMI cable for my main input (Cable).

The thing is, it’s difficult for me to wrap my head around throwing out 20’ of very expensive cable wire. I used to have a projector, which is why I had such a long HDMI cable. It was state of the art at the time.

If I could make three 6’ HDMI cables from the 20’ I have now it would be good, but only if the cable equals whatever a good quality brand new cable can do today. I assume the wire itself hasn't changed much, and if it's just the termination, it should work. I could be wrong. I wish HT would get back to me either way.

I once had them re-terminate a long power cord into two power cords and it worked beautifully.

HDMI cables have 19 individual wires and are normally built using machines.  I don't know of any manufacturer that will cut/re-terminate HDMI cables.  This is not like cutting/reterminating interconnects or speaker cables which only have 2 or 3 primary conductor connections.

If Harmonic Tech will re-terminate them for you, then great.  It is likely that the cost to re-terminate a 19-pin HDMI cable is going to actually be much more than the cable itself is worth.