Now that Nawaz is in the UK, there is no conceivable legal way to bring him back by force or pressure. There is no treaty of extradition between the UK and Pakistan (see
this as an example). His treatment, whatever you may think of it, will not be investigated by authorities here, and details of it are not allowed to be shared with anyone without the patient's formal consent.
Actually, Nawaz would never have been allowed to enter the UK as a convict, if it were not for the efforts of the government of Pakistan, and formal requests to the UK Home Office, to allow Nawaz entry to the UK in the first place. As for Nawaz's status as a convict in the UK, he has no such status here, all charges occurred in Pakistan, the court cases were in Pakistan, and even the bail was granted by Pakistani authorities, as well as the necessary procedures undertaken to allow him to travel, and the extraordinary measures to request the UK authorities to allow him entry.
So the government has already given him up fully, there's no way that I see of getting him back. Most likely scenario, he'll be back only when he himself decides to return. Things could change given a lot of effort, but I don't see any easy way.
He'll most likely get it renewed. Government would just make it easier for him to stay in the UK if they don't renew. Then again, even this is highly politicised, let's see what happens.