Resetting White 2

You could transfer them to XY if you have Pokebank.

 

White 2 is an incredible game indeed (it's my favourite, really), but to be honest, I don't think it's worth losing your first Pokémon over, unless you find some way to transfer it.
Maybe this is just me being sentimental, but for me, my first Pokémon means the world to me (a Torterra from Diamond). In fact, I've never reset that particular game, ever.

At the other hand, just getting Pokebank so that you can transfer only your Serperior over isn't worth it either. If you have a lot of valuable Pokémon, then you can consider it. Luckily, it's not too expensive (five bucks a year is a reasonable price imo).


All in all, I think you should consider to what extent you value your first Pokémon and base your decision on that.