I'm confident Kent will be here next season whether that be on loan again or permanent. So apart from that I think we need:
Quality replacement for Worrall (Cooper is the obvious option).
Squad player CB to replace McAuley.
Two quality creative midfielders. One of which id hope to be a physical box to box type.
A wide forward (Lovenkrands/Novo type)to give us an alternative to Candeias on the right.
Another quality striker to compete with Alfie if he stays.
I'm assuming Flanagan, McAuley, Worrall, Coulibaly, Davis will be leaving and possibly Lafferty, Defoe and Dorrans also.
So I reckon 6 would be enough in addition to Kent providing there are no major sells, two of which can be cheap squad players. The bulk of our budget has to go towards the two creative midfielders, the alternative to Alfie and Worralls replacement.