In the hall of mirrors, walk into the right most mirror as far as you can go without passing to the other side (use trial and error) at this point, enter "SOS' on the 'Help' key in Morse code which is "...---..." (3 stabs of the 'Help' key in succession followed by 3 presses of about 1 second each followed by 3 stabs again in succession). Your lives counter should be replaced by an infinity symbol.