You're not likely to find anything "new" with an i7 *and* a GPU.
The problem with 4th through 6th Gen mobile i7's (for the most part) is they dropped to dual-core w/HT.
Really depends what you want to use the laptop for. If for strictly gaming, a modern(ish) i5 would allow you to net you a pretty solid 'boost' over your current GPU offering, in roughly the $600 range (+/-10%).
For example:
https/www.newegg.com/Product/Product.aspx?Item=1TS-000X-00P11
https
/www.newegg.com/Product/Product.aspx?Item=N82E16834315926
Have i5-7200U (2c/4t) + a GTX 950M
https/www.newegg.com/Product/Product.aspx?Item=N82E16834154765
Has roughly the same spec, but a 940MX.... a good step down in GPU horsepower, but gets your *almost* to $600.
My recommendation, assuming the budget can stretch a little would be either:
https/www.newegg.com/Product/Product.aspx?Item=N82E16834854588
https
/www.newegg.com/Product/Product.aspx?Item=1TS-000X-00S56
i5-7300HQ (4c/4t) and a GTX 1050
*****If you look to something ~6th Gen, you should be able to reuse your DDR3L, but anything beyond that is going to require DDR4 - you could sell the DDR3L though, to facilitate the upgrade to 16GB DDR4. Anything remotely in your price range is going to ship with 8GB + GPU. If you want 16GB from the outset, you'd likely sacrafice the GPU****