The words “Once more” signify the removal of what can be shaken—that is, created things—so that the unshakable may remain.
KJV
And this [word], Yet once more, signifieth the removing of those things that are shaken, as of things that are made, that those things which cannot be shaken may remain.
ASV
And this word, Yet once more, signifieth the removing of those things that are shaken, as of things that have been made, that those things which are not shaken may remain.