That probably depends on whether or not your PD etc is already compliant with the changes without being amended.
If your COBRA for your various relevant coverages are addressed in your Cafeteria Plan PD rather than in the PD for each coverage, then you would have to amend the cafeteria PD.
If not then you have to amend the PD for each coverage eligible for COBRA.
Or, as in many cases, every one (sp) has to be amended.
Is COBRA the only issue considering all the other new laws ? HIPAA ? FMLA?
Have you amended for the new Proposed Treas Regs for cafeteria plans ?
http://www.coredocuments.com/docs/Core_Upd..._01-01-2009.pdf