Keep in mind that from the point of view of many of us here on the C & V forum there are no huge advantages to STI. The fact that you already learned to shift on this bike negates STI's primary advantage: shifting for the hopelessly uncoordinated or the unteachable. The number of cogs in the back is also unimportant. More important is having a combination of cogs and chainwheels that adequately serves your high and low gear needs.

There aren't many new bikes in bike shops that are equal to your bike for less than $1500. Assuming the bike fits you, you should consider shining it up and investing in nice tires, saddle and handlebar tape. It's a good bike by today's standards.