I've not seen any "easy" way to do this.
You could restore from a recent backup. I'd personally try to restore to another install (temporary one) so you don't lose anything current and then extract the data you need from there.
(Or even delete everything except what you need from the temporary one, then export it so you can re-import into the original - but that might be a lot of work)
To anyone who doubts that Atlassians are a little too obsessed with collaboration, and tools related thereto, let me describe a recent discussion we had (which took place on our internal Confluence, ...
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