The later model new beetles; integrated a plastic bracket into the headlight plug and this can cause connection problems to the headlight assembly (bracket causes the plug to not seat fully; thus, no power). I have cut off the plastic bracket from the plug and this has eliminated connection issues.
Bulbs failing and the wiring degrading, insulation failing is a known issue. I would start with a cicurit tester and see if you are getting power at the socket/plug and if not, troubleshoot the issue from there. Many times it is the simple things that are the problem and not something complicated, hopefully you will find the issue.
If the wiring or plugs is the issue; European Tuning by Malone and JR AutoTuning sells upgraded harenesses and plugs for the new beetle, they will custom make them for you, if the harnesses listed on the site are not correct for your later model new beetle.
Do the visual inspection of the wiring, plugs, etc. and check for power with a circuit tester; let us know the results, we can go from there. Thanks.