My first impulse to the OP was just buy another extension cord, just how expensive could it be? This should be option #3, and the price for a new one depends on the wire gauge. The smaller the wire (and the larger the gauge number), the cheaper the replacement cost.
Replacing the cord end is the safer route, hopefully you’ve noticed that soldering the two parts back together is something of a big hassle. The worst part is if you don’t get it right, the splice will drop extra voltage and cause your equipment to have to draw heavier on the power source, which could lead to burning out the electric motor on whatever you’re running.
A hundred feet of extension cord is a long ways. This should be at least 12-gauge wire if you’re running anything more powerful than a few light bulbs. I have a hundred foot 10-gauge cord I use, then run fifty foot 12-gauge cords from there if need be. It’s an expensive investment but cords last forever … if you don’t cut them accidentally … [adorable grin].
I never pull on the cord hard enough to pull the plugs apart, there’s no reason to if your handling your cords properly.
I just used Google. I’m seeing them around $30 - $40, and that’s at the stores.
Maybe you’ll argue those aren’t high quality, but we don’t know how high quality the OP’s cord is, either. Since it appears to be used for yard tools, what matters is the device with the highest amperage. Most such tools don’t seem to be all that high.
That said, I’m all for avoiding spending even $30, or buying a new cord while still repairing the old one. I just wanted to point out that it is very possible those cheaper chords will get the job done.
So it’s still spend money for a second-rate solution ($10 for a bulky replacement plug), spend a lot of money for a replacement ($25-100), or apply some basic DIY skills - admittedly, ones just outside the average home handyman, and formally foreign to electrical pros, but useful for a very wide variety of electrical and electronic repairs and projects.