Lost the spark in my eyes??!

Okay ladies I need help. This may be a little tmi, but my SO and I used to have mind blowing sex and even after our son was born it was fantastic, but this last month he says I've lost the spark in my eyes when we do it and I mean I feel like I haven't, but he knows me better than I know me.. has anyone had this happen and how did you fix it? We have such a great relationship, but I don't want that to go away because the great sex stopped..