an alternative that won't require you to recompile every time is to create an anonymous block instead:

declare
status_code char (1) := 'G';
status_desc_e varchar2(20) := 'ok';
status_desc_f varchar2(20) := 'bad';
csql_statement varchar2(200);
begin
. . .
exception
. . .
end;
/

--Simply type it all in at the command prompt