I think it depends on what exactly you're changing and how big of an impact it'll make on your story. It also matters how far in your project you are.
If these are big glaring issues, I'd fix them regardless of how long they take. If they are small things that may only be nit picky, I'd just try to keep an eye out for them going forward.
Then again if you aren't that far into your project, it wouldn't hurt to go back and make corrections even if they are small.