Need to Reload a Dump File - Need to Delete the PGDATA directory Again?

Hi All,

I'm in the processing of migrating to Postgres 8.3.8.
I did  :
(1) initdb
(2) psql -e template1 -f 21.bak &>/tmp/out21.bak

Now, I've  decided that I want to reload the same file again, do I just delete the PGDATA directory and then
perform the same steps again?
(1) initdb
(2) psql -e template1 -f 21.bak &>/tmp/out21.bak

What I'm asking is that do I always need to delete the PGDATA directory and then initdb to ensure that it will be a
cleanload? 

Thanks
Mary