Kentico is actually already compatible with the Graph 2+ API. The problem here is probably in a way that Facebook "mysteriously" handles API versions. What I mean is that whenever you create a Facebook app, FB will automatically assign you a API version which is currently up to date. You can see that in your App dashboard on facebook. I have also attached a screenshot from my own app for a reference.
I'm not exactly sure how would FB handles the version, but from what I believe it should be automatically transfered to a higher version (developers.facebook.com/docs/apps/versions).
Our customer which created their FB app later when the Grap 2 API was available have no troubles with this whatsoever. I believe that you shouldn't have any troubles as well but you can still try to re-register you app once again, so it should start using Graph API 2.0 automatically.
If for some reason the API calls will stop working, try contacting Facebook support so that they manually change your API version.