I would sudgest taking a look at Joe Matlock as a possible backup for your defence, another good young player you might find is Miles Addison from Derby County, hes always predicted to be the next Gerrard for me, and maybe another backup striker would do the trick, John Fleck maybe?
Your main squad looks to be preety could, as you said, you won every comp last season, so I don't think you will need to make any major changes. Probably just ensuring that you have a big enough squad ready for the long haul through the season. That is my main priority in the transfer window...nothing worse than having to play players out of the natural posistion when your expected to win everything!