I am looking into the same question and have thus far not been able to find any guidance regarding whether the new rules under MPRA Section 105 for determining the target funding percentage should apply to FIPs already in effect prior to 12/31/2014.
There are other provisions of MPRA with the same effective date that would appear to apply to FIPs (or adoption periods) in effect prior to such date.
In the absence of a clear provision in Section 105 excepting plans with FIPs commencing before 12/31/2015, I am inclined to say that existing FIPs need to be updated to comply with the new rules. For many plans, such as yours, the stakes are high for how this question turns.
Any thoughts or insights from the community would be appreciated.