Making upgrades to my Bianchi Limited (ie better wheels / tires, bottom bracket, pedals) or looking for a better (perhaps newer / lighter) road bike?

Currently it is running Araya 27 x 1 rims with with some ultra light tires (can't know of the name). Needs a new BB. And the pedals are hand me down Wellgo magnesiums. Right now it is around 23lbs and is comfortable.

The reason I am thinking is I am starting to get more into it and am going to have about $500 available if I want it.

Just thinking out loud...and wondered what input you all would have.