There’s no shame in doing DLC for this game
A recurring comment from interviews with the developers of this game is something along the lines of “there will be no microtransactions and no DLC, we wanted to include the full experience of the original game for one cost at launch so players can enjoy what they loved from the first game without any additional hassle.” But I think this line of thought may be missing the forest for the trees. No one wants microtransactions like those present in PvZ2, where players have to shell out insane prices just to receive a single plant, or even worse, regularly pay to simply refuel their energy to be able to attempt a certain mode. These kinds of systems are predatory and unwelcome, but not all DLC is like this.
Often times developers discover that a deadline is rapidly approaching and they don’t have time to fit in every last one of their ideas for a game before the scheduled launch, so they develop DLC after the initial release that revisits these abandoned concepts. Or they could just want to do more with their project after the fact. In these circumstances, releasing additional content for a fair price isn’t only permissible, it’s welcome!
In the case of Replanted, there is still a lot that longtime fans would love to see done with this remaster that the series never really touched on afterwards. What about console-exclusive minigames like Buttered Popcorn and Air Raid? What about additional lawns for VS mode like Roof and Pool? What about a new world entirely with new plants and zombies to discover? DLC opens the door for it all, and so long as the content is substantial and you don’t overcharge for it, no one in their right mind will complain. The beauty of it all is that you’re free to develop post-launch at a more relaxed pace without as much worrying about meeting deadlines. I know you’ve already said you won’t do it a few times, but really you can just say you changed your mind and got some ideas for DLC support that you didn’t have time to fit in the game before release. Again no one will mind so long as the pricing is fair and nothing in the base game is locked behind paywalls.
Just some food for thought!