Is it permissible to repeat Salatul-Istikhara regarding marriage to a girl after the love for her has faded following the first Istikhara, due to longing for a past love?

Repeating the Istikhara is permissible, but there is no need for it if one's heart feels at ease with not marrying after the first Istikhara. It is permissible to do something even if one's heart does not feel at ease with it after the legitimate Istikhara, because it will be good, Allah willing. It must be noted that a man's love for a woman who is a stranger to him is forbidden.