The best route is exactly what you have done - post in here, or flag to moderators. We'll get a good look and take one of 3 actions:
- leave as is (default, especially if the old answers are ok) - possibly add a link to point from the old one to the new
- change the dupe direction (if the answers on the new question are much better)
- merge (if there are good answers on both sides)
In this case it appears a merge is likely to be the best bet as there are a few good answers on each.