The main way I know to force an update to the cache is changing the prefix-key, but AFAIK that will start from scratch instead of reusing an old cache entry.
I'm trying to debug why some dependencies are being rebuilt and it would be a quicker debug process if I could reuse the current cache when updating the cache (ofc if I'm able to identify the issue, I would want to do a final test from a clean slate to make sure things aren't just working due to the cache built up during debugging).