Tips on how to increase amount of sex we have without taking the "fun" or of it.

Since having our first daughter 2.5yrs ago, my partner and I rarely have sex. like maybe once every 4-6 weeks. Neither of us are bothered by this, however it is making TTC difficult. We certainly are not having enough sex each cycle to really have a good chance of conceiving. Any advice on how we can make sure we have more sex in my fertile period without making it too stressful / planned ?? thanks