There have been many similar threads so maybe have a look and see what advice was offered then. Usually the lack of sex is a sign of a bigger problem in the relationship, a healthy functioning guy should want sex on a regular basis. You need to tell him this is an issue for you and your needs are not being met. He needs to respect the relationship has an issue and play his part in sorting it out. Personally I think no amount of sexy lingerie or spontaneity is going to help until you find out what his issue is. Is he bored? Has his feelings changed? Is he depressed or stressed? Is he masturbating too much and therefore not 'needing' sex from you? You need to find out the reasons and he needs to tell you. Only then will you find a solution. If you were like rabbits in the beginning then he is capable of it and does find you attractive you both need to work on getting back to that point.
Some people are drains and some are radiators... Keep clear of the drains and hug the radiators!