No, Manjaro is a rolling distro: if you update it regularly, you should never have to reinstall it. "Regularly" typically means at least once once a month (though I've gone about three months without updating it and nothing broke when I finally did it, but that was pushing it a bit). If you neglect updating it for a long time, there is a chance an update will break something and fixing it might just be so complicated that it's easier to reinstall it.
The problem with using an old image is that images do not receive updates (being fixed in time). An image installs Manjaro in the same state as it would be at the time that image was released: in other words, as if it has not been updated ever since then. So if the image is a year old, and you install it now, that's the same as installing it a year ago and not updating Manjaro since. That usually means trouble.
But as @firefightux pointed out, you have nothing to lose with a fresh install (apart from some time) if you try to update it, as you can always reinstall.