There is no dua as such mentioned, because Allah has preplanned this love to enter after marriage as a gift ready between the spouses. It is only the fault of each or both that spoil this through their actions. To make it appear strong again is to polish the soul with good actions and mercy and care for each other. Search for it and you will see it. There is a verse of the Holy Quran that says,
And those who say, "Our Lord, grant us from among our wives and offspring comfort to our eyes and make us an example for the righteous." Furqan :74
This verse was recited in the qunoot of the prayer of the Holy Prophet (s.a.w) everyday. This will surely make a difference in your married life if you are steadfast in reciting it.
Try to recite it with your family together whilst raising your hands above your heads as suggested by ulema.
Encourage her by requesting her to present herself the way you like maybe through explaining her about your choice.
If you don't feel the way you want or expect to, ignore it and keep on trying and praying, im certain things will change because of your goodwill and intention.
Your actions and kindnesses will make her glow with the inner beauty which keeps growing and never fades like the outer beauty. This is the principle in life, all are attracted to the inner beauty of a person rather than the outer.
InshAllah you will both experience and share this deep love and devotion towards each other.