In some cases, the feeling of having "lost your mojo" as it were can be caused by one of two different things. It can either be caused by large amounts of stress (often revolving around money or a disagreement), or it can be caused by a lack of sexual adventure. In the cases of lack of sexual adventure, there are two different ways you can "cure" that. On the most part, keep an open mind and try new things. Perhaps a different position, place, theme, or setting may provide a refreshed sense of interest. As well, sometimes trying different things, regardless of whether or not they're "kinky" such as exploring your partner's body, seeing what makes them go "oohhhh", etc. may be that extra little bit that suddenly adds that sizzle all over again. The same can also be done when same is done by your partner. The other option is open communication. In some cases, clear communication of any form (be it verbal or not) is the best way to enhance a sexual experience. For example, recognizing both your and your partner's "oh baby" spots is a very important key in the sexual pleasure, especially when the knowledge that you/they are hitting that "oh baby" spot increases the sexual feeling mutually.
The most important key is to discover the things that "do it" for you. Keep in mind as well that there's more to a relationship than just the sex. There's also a care and compassion for your partner (well… unless it's a 1 night stand) and the vibes that you get when you're with them. Just because a sexual drive may decrease, doesn't necessarily mean that there's no feeling at all left. One of the best ways to get involved is open communication. If you and your partner do not actively and clearly communicate, there may be things that act as that "stresser" that decrease the sexual drive between the two of you on both sides. The only way to correct this if this is the case is through open and honest communication.
In the end, only time will tell. As well, as the old saying goes, "If you love it, let it go. It if come's back, then you know it's right. If it doesn't, then it never was." I do not know the author of that comment, but it is definitely very true. I hope all the best for you 