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I think You rather should just watch the manga based episodes. The rest are fillers and do not contribute to the plot at all. The manga plot itself also didn't move forward much (and You will find here plenty of people who will say that it didn't move at all), so if You have any recollection of what happened up until the episode 500, then I think You rather should be fine. However, I would suggest You rewatching the Clash of Red and Black, because You might need to remember the events that happened there.
For episodes that are based on manga look there: http://www.detectiveconanworld.com/wiki/Anime
EDIT: I also would suggest You (after watching the most recent episode based on manga) starting to read the manga, unless You want to wait centuries until they will catch up. Gosho recently been hospitalized, so expect a lot of fillers...