i am not a lady, i am a husband who has gone through this. i think as men, we have to continue to work to be the most attractive man we can while also being a great lover. she will up her game as you up yours.
also, foreplay should last all day. give her a long, deep kiss when you get home. make her feel sexy throughout the day (texts, emails, and phone calls). sex has to be on her mind more often than when you request it just before bed. get to know her cycle. ovulation is usually 12-16 days after the first day of her period. be aggressive around that time. she should be more receptive. you may have to work harder at it around days 20-28 as she will be less receptive and less orgasmic.