How does Mrs. Bennet further reinforce that she has not grown or changed as a result of recent events?

Rather than focus on Lydia's shameless behavior, Mrs. Bennet is ecstatic is hear the news of her daughter's upcoming marriage (forced). She begins to think about ordering wedding clothes.

Mr. Bennet informs his wifethat he will not receive the couple at Longbourn, nor will he give Lydia money for wedding clothes. Mrs. Bennet is more disgraced by her daughter's lack of new wedding clothes than she is by Lydia's elopement.

For Austen, the alternative to superficiality seems to be strong individuality and virtue. Lydia is only concerned with her own immediate happiness and her public image, which causes her to nearly ruin her family's reputation. Mrs. Bennet's happiness after Lydia's engagement is comically narrow-minded, proving her utter lack of moral direction. Lydia and Mrs. Bennet's behavior is the opposite of the moral virtue that holds a community together. The community, through word and example, inculcates those virtues in its members. A serious breach of virtue on the part of one person is an injury not only to that person's character, but also to the characters of all his/her close relations (especially since the older relations have an obligation to educate their children). In Lydia's case, her lack of virtue seems in large part the result of her mother's foolishness and her father's indolence, but also of a society that demeans women and praises petty materialism and gossip over strong individuality.