Replacement NIF card

Assuming UK passport holder, yes, you can get it replaced by applying for the new plastic / biometric TIE card.  As you are permanent resident card will be valid for 10 years at which point it will have to be renewed (bring holders of TIE into line with Spanish citizens who have to renew DNI card every 10 years)

Although not mandatory … yet … it’s probably a good idea to get a TIE anyway especially if your NIE card is getting dog eared and hard to read.

Thanks but I’m not a permanent resident and haven’t got a residencia only the NIF

Does this make a difference?

Ah. Yes.  The paper certificate the NIF is issued on is only valid for three months anyway - you’d need to get it re-issued.  Same number, obviously, just a fresh certificate, but you MAY need a reason to request one (i.e. making a purchase of vehicle etc). I know with non-resident NIEs you can’t just get one issued - you need a reason; it’s possible the same applies for re-issue of certificate.