Welcome back to the community , glad to see you kickin again and happy a new year btw :D

If I'd give my opinion would be better start a new server.It would be more fun and would help you once again to feel again being active in game since s315 is an old one and the guys in your server are much more stronger and cultivated their power through these years.So being competitive again means you should start anew.

But theres the other side , if you feel you have invested a lot in your ninjas and your current account ,, if there are friends you still have there then the best choice would be to stay.It depends on your choice.

But personally id reccomend you to once again enjoy the new servers atmosphere it really helps you and makes you enjoy even more this game. :D

Hope it was helpfull.