Smileys in older topic wont show after upgrade from 3.0.13 to 3.1.13

I've upgraded our forum recently. After extensive testing, in my DEV area, didn't found any issues. On the live environment I'm now facing the fact that smileys are not working on older topics.

I've noticed that all smileys will fail in such topic - also if a new post is done.
New topic, smileys work without issue.

I've noticed that editing a topic, and then save it solves the issue.
With close to 2000 topics, its a bit hard to do this everywhere.

Basically the ~2000 topics will need to be re-parsed, but not find a way to do this other then manual.

I've followed the upgrade instructions as posted on phpbb.nl (dutch translation of the official one).

Thanks in advance.