hi,
I cannot understand what does your code do in the whole?

POP R0 ; pop! <- use AR0
ADD R0, 1h    <- what? do you mean
                 ADD R0,AR1 / INC R0 something else?
PUSH R0       <- AR0
RET           <- wow,

I see: does your code just
modify return address? Why not use JMP (over part of code) instead call such subroutine? I totally have no idea whatta you need...
Good days!