Numeric permalinks altered in upgrade

In the course of upgrading from 2.2.2 to 2.5.1 some of my Pages were transformed into Posts and this screwed up the numeric sequence of my permalinks (I use …/archive/45 etc.) I’ve deleted the erroneous posts, but the numbering did not change back. In the new database, however, the original numbering seems to be intact.

How can I return the permalinks to the original numbering (so it matches numerous links I sent out into the world.) Thanks.