updating IDs after delete  is considered a very bad practice. i suggest u not to do that. there are ways like:
lock the table, fetch the whole table, write the records  again with new IDs.
but u have to free ur design from this.
a better way is to have a code field  and work with that.
if u delete a recorde u may find the deleted code and reuse it.this has nothing to do with the ID.
Have More Fun.

Basically, when you're using AutoNumber for your table, you are implicitly creating a dummy primary key for your table without counting on further modification of this field  and you haven't any concern about the values. If you need to manipulate your key values (update or reuse them), then you must go for manual code generation through your program. It always recommendable.