How to update the authentication cookie that MS Excel sends to a webdav server?

Hello, We have a webdav server that communicates with MS Excel (and similar applications like Word, Powerpoint, etc.).

All is good, however, one problem is that the authentication cookie we have expires, and when it expires, any further attempts to save would result into an error.

As a response to that, we try to send a new authentication cookie every time MS Excel sends a refresh lock request, in hopes that it would discard the old cookie, and use the new one, thus extending the user's access. However, MS Excel still sends the old one.

Are there extra steps we should take in order to get MS Excel to use the new cookie?

Thanks!