This is the first and the biggest mistake. If you really want the spark and want to spice up your love life, just do not take your partner for granted. Few things you can do to revive your love life.
You should see that you are lacking in your effort. First of all look at your fault instead of blaming your partner for each and everything. Healthy relationship means taking care of yourself and your life partner. Do not treat him/her for granted. See your figure whether it is right or not. Staying in shape will attract your partner towards you. A good sex life is an important part of a healthy love life. Just don’t waste time, go get the right shape.
Come out of the routine sex. Try something new. You and your partner will love the change. You can take ideas from novels and other materials. Try that you have never done before, surely you will be benefited.
Do something that he/she likes. Do that you use to do long before to make your partner feel happy or make him/her feel special. Romance does not start from bedroom. Plan a romantic music with romantic candle light dinner. Surprise him by doing something new.
When relationship starts, you take much time to learn about him and now also you should know about his/her new likes and dislikes or new hobbies and generate your interest in your partner and you will get same emotion back. You will see your bonding will grow stronger and more beautiful than before.
Spare time for him/her. Go out for dinner. Do not take anyone else even your kids. It should be just you two and love. You will see the difference after dinner. Talk about just love and your happy moments.
Do something that he/she appreciates about you. Wear dresses that he/she likes on you. Dress like when he/she saw you for the first time. Give your partner a thrill.
You can read love poems with your partner. Write some love notes on his/her mail. It will make him/her feel that he/she is special.