Now if truth be told, it seemed like an obvious gag. If nothing else, the original Robocon series was called "Ganbare!! Robocon" and now in the Reiwa era they were going to make a movie called "Ganbareiwa!! Robocon". The pun-based name just made it seem sillier.
And yet... it seems that perhaps it isn't a joke. The twitter trademark bot that gives us all the usual toku show names has popped up with an application (see here) by Toei for "Ganbareiwa!! Robocon" in a variety of categories, most of them related to merch. So it does indeed look as if Toei are planning on doing something with the title again.
To save you some Googling, Robocon was a comedy toku created by Shotoro Ishinomori back in 1974 about a funny little robot that could turn into a car. The original series ran for a mighty 118 episodes, longer than either the original Kamen Rider or Goranger! A reboot called "Moero!! Robocon" aired in 1999, between the final Metal Hero series and Kamen Rider Kuuga. The later series also had a straight-to-video VS movie where the new Robocon met the original.
The original announcement said that they were going to release a movie on July 31st, which seems rather unlikely with everything going on in the world right now. But who knows, maybe it's time for this little robot to get a third outing?