I agree! While you're waiting for your body to recover engage in lots of foreplay and make her orgasm from oral and manual stimulation. Also, you could masturbate beforehand and then engage in sexy time - numerous sources have told me this can make you last longer.
Also, has your partner brought the quickness of your sessions to your attention? Or are you just worried that she thinks it's not lasting long enough? Sometimes I think we're overly critical of ourselves, especially when it comes to the ability to perform in bed!