I don't import markings. I treat a newer version as a new document, and mark it up fresh: that requires reading the flight release, without assumption. What's changed since the last version?
Ever had a route change since the previous version? New fuel numbers? A volcano? Changes in overflight permits? NOTAM changes? TFR's?
Run down the new flight release and see what's changed. The old markups may no longer be valid.