Renewal of an Instrument Rating (Aeroplane), within a period of not exceeding 5 years from the expiry date of the rating then a proficiency check is required to renew. If 5 years has been exceeded, then an Initial Instrument Rating Skill Test with a CAA Staff Flight Examiner is required.
Probably not worth renewing unless you want to do a Type Rating, if you are currently hours building you can remain IFR brained in VFR conditions anyway.