There is no vector you can jump to or instruction to effect an MCLR Reset.

You can cause the Watchdog Timer to time-out (if you've set it), but a watchDog Reset isn't the same.

The easiest way is to cross-connect a spare PIC pin (the one adjacent to the MCLR pin is a good choice!)... since they all power up as INPUT by default, all you have to do is OUTPUT your chosen pin LOW. Don't forget to TRIS your chosen pin as INPUT (until it's needed) and if you choose RA0 (as the adjacent pin), don't forget to set it to Digital Mode.

See the RESET sub-section of the "Special Features of the CPU" section in your PIC's Datasheet for details of the state of the internal registers of your PIC following any given Reset.