You would have to do the initial skills test only when it has expired by more than 7 years.
Not quite correct. Be very careful, it is 7 years from the last reval/renewal, not expiry date.
(c) Renewal. If an IR(A) has expired, in order to renew their privileges applicants
shall:
(1) go through refresher training at an ATO to reach the level of proficiency
needed to pass the instrument element of the skill test in accordance with
Appendix 9 to Part-FCL; and
(2) complete a proficiency check in accordance with Appendix 9 to Part-FCL, in
an aeroplane.
(d) If the IR(A) has not been revalidated or renewed within the preceding 7 years,
the holder will be required to pass again the IR theoretical knowledge
examination and skill test.