Policy Expiration Date and Cookie Expiration

We are trying to implement a P3P policy, and we have some questions =
about the expiration dates on cookies. =20

Given the following situation:
We set a cookie on 11/01/2003 that expires in 1 year.   We want to have =
a shorter expiration date on our privacy policy so that we can change it =
if necessary, and we overwrite the cookie with every page hit. =20

Do we still need to set the expiration date on the policy to be as long =
as the cookie expiration date?  I read somewhere that as long as we =
reset the cookie each time, this is not necessary.

Many thanks for any assistance on this.

Megan Cross