The quality of every Spongebob episode has increased up until the first movie, but after the movie, the show quality has gradually gone down with each episode. In order to be close to as good as the first movie, it must have an amazing plot and new, exciting jokes that haven't been overused.
Now i not saying it will be bad. Its likely to be awesome, but the first is so far the the best nickelodeon show based movie by a long shot. And the quality of spongebob squarepant episodes today is very very very poor. And they may have waited to long to make it.