If this is to happen, 2 strikers and 2 midfielders in. Maybe a left sided midfielder who can also play LWB. Stick with the current defenders we have until the summer.
If the above comes off the outs would be Hanson (permanent), Lavery (Loan with a view to permanent), Thomas (loan). I don't think Lavery is an out and out striker, he's more of a winger and to be honest don't see where he fits into the current system, Hanson isn't very good and his ability in the air and holding play up just isn't enough against Championship defenders. Thomas needs game time if he's to start taking over from Duffy next season.
Carruthers to leave in the summer, unless he improves, if we need to keep using him this season his value and saleability will increase for any League 1 club interested. A loan with a recall clause would be another option.