Hi Achilleas,
I'm not a very experienced professional to suggest you, but I'm putting forward my views.
If you feel that you will be successful in getting re certified, you may consider working in SAP field again.
Since you have worked across different domains, you must be knowing which one gave you most job satisfaction. I feel that you should move on with such domain.
Of course, there is no best way. It depends on what you will choose and how you pursue it.
All the best.
Regards
Nikhil