GOTO Lsetup

I'd like to be able to code a GOTO LSETUP statement in the LOOP function to branch back to that label coded at the beginning of the SETUP function. At this point I believe the language actually prevents that from being syntactically allowed. Provided I can overcome the ISP compiler errors; I'd like to know if my UNO will be damaged or work at all? I'd like to use this technique to re-initialize the sketch. Before doing so, I'd expect to send a signal back back to the PC to let it know that a programmed restart of the sketch is about to be performed so that the PC can re-synched to a corresponding state with the UNO.
Barring that, I'm considering having the reset pin driven by a pin of the UNO to simulate a physical RESET button press.
I'm hoping this approach is a way of controlling the electronics if they get into too much trouble they will be in a remote location.
Any suggestions will be appreciated.

You can't jump between functions, and I can't think of a situation where you would want to.
You can call "setup" from "loop" but you can't call "loop" from "loop"

You can call loop() from loop(), but unless you take particular
care to prevent unbounded recursion you'll just crash the chip.

I'd strongly recomment not calling setup() from loop(), its poor style,
reserve setup() for power-up and reset-time actions, and write yourself
a restart() function that you can call from setup() and from loop(). There
may be things you only need to do at power-up and (hardware) reset.

If you really just want to restart the entire sketch I believe you can do a software
reset with this code:

void software_Reset() // Restarts program from beginning but does not reset the peripherals and registers
  asm volatile ("  jmp 0");  

Only the Mega AVRs have the "jmp" instruction.
The Tiny range only have "RJMP" and "LJMP", so will not work on the 2313, 24/44/84,85 and so on.

There is also the setjmp and longjmp() C commands.

You want the watchdog timer for this. When you hit an unrecoverable error, serial-print your dying gasp message, enable the watchdog timer, then spin in a while(1) loop until the timer expires and resets the IC.