You either need to do the IR exams or the ATPLs again. If you decide to do the IR exams only for the IR issue then, according to my understanding, you will need to do the ATPLs again
as well before you get your ATPL issued. If you re-take the ATPLs at this stage they will count for the IR and, with an IR issued, the ATPL theory will be 'frozen' in anticipation of you eventually getting an ATPL.
If you ask the CAA on
[email protected] they will probably insist you to take an approved course for the ATPLs but allow the time taken on the course to be reduced at the discretion of the Head of Training.