However, because of a series of injuries, Riggott was recalled from his loan spell and played a big part in helping Boro secure their Premier League ststaus during the final couple of games.
"I have said to him that I have learnt a lesson. I left him out on reputation and we lost," Southgate told The Gazette.
"I said that that will not be the case next season. I learned I need to pick the players on form, so it is much more open now.
"That does not mean I guarantee anyone first-team football, but he maybe thought it was an uneven playing field last year and that won't be the case from now on.
"If he says to me 'look, I still feel as if I'm not going to get as much first-team football as I want', then that's his prerogative. But I think he will end up playing football here."