If the current tank is 6 months old give or take, everything should transfer over with little issue. You may need to rinse your sand, but unlikely.

I would suggest picking up a bottle of BioSpira, to really help kick up the new tank and some bacteria.

Other than that 46 up to a 55 isn't much of a jump, kinda just like a big water change. Only other thing you'll really need is a bigger better light.

Good luck keep us posted!