oreplace

DECLARE
v_clob CLOB;
BEGIN
FOR rec IN (SELECT ROWID rid, my_clob_column FROM my_table WHERE my_clob_column LIKE '%EOLN%') LOOP
v_clob := rec.my_clob_column;
v_clob := REPLACE(v_clob, 'EOLN13', CHR(13));
v_clob := REPLACE(v_clob, 'EOLN10', CHR(10));
v_clob := REPLACE(v_clob, 'EOLN160', CHR(160));
UPDATE my_table
SET my_clob_column = v_clob
WHERE ROWID = rec.rid;
END LOOP;
COMMIT;
END;
/