Does the plastic plug body have little square/rectangular holes on one of its flat sides?
The end has a tab sticking out that fits into that hole and holds it in place. You can use thick needle or craft knife or somesuch to push the tab down to disengage it, while at the same time pushing out (toward the "wire" end of the plug) to work the end out of the plug body.
Once out, fine-nose pliers to crimp the end back onto the wire (better yet, solder it on first) and the craft knife to lift that tab back into place: you probably bent it too much in while getting the end out.
Then push it back in until that tab clicks. You'll probably need a fat needle to help with the pushing.
If you never done this before, keep in mind that I have, many times, and I give myself about 60-40 chance of succeeding. If your connector has an opening for that little tab: some (bigger ones usually) have just a notch inside without a hole.
The end has a tab sticking out that fits into that hole and holds it in place. You can use thick needle or craft knife or somesuch to push the tab down to disengage it, while at the same time pushing out (toward the "wire" end of the plug) to work the end out of the plug body.
Once out, fine-nose pliers to crimp the end back onto the wire (better yet, solder it on first) and the craft knife to lift that tab back into place: you probably bent it too much in while getting the end out.
Then push it back in until that tab clicks. You'll probably need a fat needle to help with the pushing.
If you never done this before, keep in mind that I have, many times, and I give myself about 60-40 chance of succeeding. If your connector has an opening for that little tab: some (bigger ones usually) have just a notch inside without a hole.