This code is adapted from Euclid. It refills your magic by 1 point (max: $80) every 256 cycles ~ 4 seconds (roughly).

Code:

lorom

org $808056
JSL freespace

org $A2F4D0 ;some free space in All-in
freespace:

;optionally require book mudora for auto-refill. remove the semicolons if you like this restriction.
;LDA $7ef34e
;BEQ end


LDA $1A
CMP #$7F
BNE end
LDA $7EF36E
CMP #$80
BEQ end
INC A
STA $7EF36E
end:
JSL  $8080B5
RTL

You can compile the code with the restriction of autorefill only if in possession of Book Mudora.

Patch files:
http://bszelda.zeldalegends.net/stuff/Con/magic_autorefill.zip