It will get better, but it may take a while. Like another poster noted, when you return him to bed, don't speak to him or engage him at all. Just gently and firmly turn him around, guide him to bed, tuck him in and walk out -- don't even repeat the "night-nights." You will feel for a while like this will never end, but it will.
Be sure he's not getting up because something in his room is scaring him; some kids don't cry or get upset but do get wakeful if something in the room is unusual or scary. Remember, a nightlight that seems lovely to you may seem to him to cast weird shadows, or a blanket hanging over the back of a chair that's there all day may look like a monster at night in the dim light. He's probably too young to articulate any concerns like those but look around his room from the new position and height of his toddler bed and think if anything might seem weird or scary from his perspective. Otherwise -- keep on putting him back, without any engagement. He'll soon realize it's not a game and there's no use in trying to play it!