While owner Ellis Short is keen to avoid making wholesale changes in the summer, O'Neill is still likely to add a few more new faces.
O'Neill told the Sunday Sun: "We've still got a lot of work to do here.
"The last thing I want to do is to talk about projects and what have you, because you don't get time for those.
"We're trying to improve the team and it's a balance with some players coming in and some leaving.
"We're still slowly but surely changing the side around and seeing it evolve.
"I think the owner has said he doesn't want it to be like a revolving door here, in terms of signings.
"I understand that, because there have been big changes in personnel in previous years and he doesn't want to do that again.
"But of course sometimes you need to make a few changes to improve the side."