What to do after beating the game

So I've completed the game, and usually after I've completed a game, I don't tend to play it over again(unless there's a new game+ version), but I absolutely love the game and want to continue playing it. I see others who have played the game over and over and over and I'm just wondering what do you guys do in your new games? Do you just try to Speedrun it? Do you try to challenge yourself by only using a certain amount of materials? Give me some ideas to challenge myself

Edit: I'm on PS5