We need an experienced midfield dynamo, who has the energy and enthusiasm to get rapidly from box to box. When I think of this type of player I think of Steve Castle and David Friio (if only).
I saw Craig Tanner do it in the JPT against Exeter and I longed to see him do it again but it didn't happen. I have occasionally seen opposition players do that against us; most recently, it was a Wimbledon midfielder who caught us out. I also think that Liam Sercombe (Oxford) is that type of player. Curtis Nelson is capable of making these runs but he cannot neglect his defensive duties and, in any event, his distribution needs to improve.
If we had a player like that with Graham Carey spreading the passes around, I think that Gregg Wylde would be more effective. He is criticised for his final pass but, often, when he gets to the by-line, he has only one colleague in the box to try and find.
With regard to the players who should remain, I would say McCormick (with a serious alternative), Nelson, Hartley (with a serious alternative), McHugh (of course), Carey (of course), Wylde and Brunt. I would also like to see Matt persuaded to sign. I suspect he will also attempt to sign Jordon Forster, expecting him to challenge Hartley in central defence.
I really am not sure about Reuben Reid because I am confused about his relationship with the manager. If there is a problem he should be allowed to leave and replaced with a natural goal-scorer (easier said than done).
The manager knows which of his younger players he wants to retain and, as I have not seen them, I would rely on his judgement. At least, he regularly watches games that they are involved in.
So, I don't think that we need an entirely new squad but there would certainly be room for several additions.