Second verse, same as the first, Kharonne! Follow the link Paul gave to Allen Browne's page. Allen gives a somewhat complicated method, that has the advantage, I believe, of carrying forward all data form the previous record to the next new record.
which is a much simpler method, but needs to be done, individually, for each field that needs to be carried forward. Since you're only talking about one field, this is probably the way to go.
I tried both of these methods, but neither seemed to work for me. the second one, when I complied in Access 2003, gave me errors. The first one, I tried just did nothing.