PIC12C672 Replacing Upgrading to PIC12F683 RT809F PROGRAMMER
It seems you can pick upgraded PIC chips such as PIC12F683 or PIC12F675. Two things need to be considered before you pick chips in your case. 


Pin placements and configuration
Electrical Specifications


Both requirements have been fulfilled in the newly selected PIC Microcontrollers. 

Pin Placements and Configurations:



When you see these 3 MCUs, all of them have a pins with same functionality at same place. So, replacing the MCU will not create any connection problem here. 

Electrical Specifications



Here electrical specifications are also compatible with the old one. So, you can choose any one of these two what you can afford. 

When you look at specifications, PIC12F683 does have more heat dissipation capacity(800 mW) and Maximum source and sink current of GPIO pins (200 mA) than other two MCUs which might be an extra benefit if those conditions are met in your circuit.