How do I Remove a value stored with && ?

[kmesser]

In SQL*PLUS, I'm developing a procedure. As part of the procedure, I have a value I wish to prompt for once, then use repeatedly. Now I don't get prompted any more and I need to change the value.

declare

cursor x is select * from mytable where id = &&ID;

begin
. . .
end;
/

How can I "undefine" this value?