I've seen quite a few posts about sex becoming businesslike whilst ttc. We've only just started trying and DH already felt a bit like he had to perform on demand. I was like Get with the programme 
I have though bought a new slinky black nighty thing (Rosie HW for M&S), bought some, ahem, handcuffs
and we've watched a bit of porn together to get in the mood, which we would never normally do.
Are there things you and your partners do to keep things fresh?