The Silver Samurai cuts through Logan's adamantium claws and starts draining his healing ability. After Mariko intervenes, Logan grows bone claws and uses them against Yashida.
He doesn't regrow the adamantium coating with them. That's an important limit people can skip when they talk about him regenerating. The metal was added to his body. The claws underneath it are part of him.
Days of Future Past later shows adamantium claws on the future Logan again, but that movie doesn't show us how he got them back. We can point out the change without inventing an operation or pretending we watched the healing factor manufacture new metal.
The movies leave some connecting details out. Filling those gaps with an explanation that sounds plausible doesn't turn the explanation into something confirmed on screen.
The Silver Samurai cuts through Logan's adamantium claws and starts draining his healing ability. After Mariko intervenes, Logan grows bone claws and uses them against Yashida.
· Film and Television / Marvel