Split String which has space and replace spaces with "/"

Sample String "ABCD123 ETS, NM"

UPDATE TABLE_NAME
SET COLUMN_NAME=SUBSTR('ABCD123 ETS, NM',0,4)
  ||REPLACE((SUBSTR((REPLACE('ABCD123 ETS, NM',', ','/')),5,INSTR((REPLACE('ABCD123 ETS, NM',', ',',/')),',',1)-4)),' ','/')
  ||REPLACE(SUBSTR('ABCD123 ETS, NM',INSTR('ABCD123 ETS, NM',',',1)                                                        +2),'NM','NEW MEXICO')
WHERE CONDITIONS;