Nothing short of a parade of guillotines could have made OWS successful.

One problem is that it's a supreme court decision, and the only way to "repeal" those is a constitutional amendment, which requires support of a 2/3 majority of congress, or a new set of supreme court justices to make a new decision, but those are lifetime appointments and so you may have to wait decades for an opportunity. Realistically the only options are workarounds because a literal repeal has a very high barrier that's unlikely to be overcome even with a very successful mass popular movement.

if Occupy Wall Street had made repealing Citizens United as their main platform

It would have been ignored, just like all their other platforms.

OWS was a moment for progressive organizing and collective altruism. But the biggest benefits of the movement came from their Rolling Jubilee, their local collectivism leading to shutdowns throughout Manhattan and other big urban centers, and their educational initiatives to turn the tide on anti-socialist propaganda.

This was never a Congressional lobbying operation. It wasn't designed to be.