The LIFF SDK keeps a permanent link for the current page. We'll publish the documentation of the API that handles this permanent link.
liff.permanentLink.createUrl()liff.permanentLink.setExtraQueryParams()
These APIs are already included in the latest LIFF SDK, so the LIFF SDK version doesn't change.
For more information on how to get a permanent link, see Get a permanent link for the current page in the LIFF documentation.