MEP can be revalidated in flight only
In accordance with FCL.740.A(a) for revalidation of multi-engine class ratings and type ratings, the applicant shall:
pass a proficiency check in accordance with Appendix 9 to Part FCL in the relevant class or type of aeroplane or an FSTD representing that class or type, within the 3 months immediately preceding the expiry date of the rating; and
complete during the period of validity of the rating, at least:
10 route sectors as pilot of the relevant class or type of aeroplane; or
1 route sector as pilot of the relevant class or type of aeroplane or FFS, flown with an examiner. This route sector may be flown during the proficiency check.
So simply multi engine class rating can not be revalidated by experience and can not be revalidated in simulator.