Enter prohibitions (and break them).

One of the proven methods to return passion is to introduce a temporary taboo on routine activities. For example, cross out the missionary position for a month. Or agree that in the next 10 days only kisses are available to you, and it is absolutely impossible to switch to sex. The very fact of the ban, as you know, has an exciting effect. Chances are you won't last that long. And this is good!