It is funny how many people say that you just call your partner by his/her name. If you want to keep the fire burning, get a name for him/her. You can go an extra mile of spicing it up with change in language.
For example, the word love in German is Liebe, you could decide to call him/her that.
If he is from a certain tribe, try calling him a different name in your tribe, especially if he/she is not well con-servant with the language.
Remember this, love grows old if new things are not brought up. Do not get too comfortable with one another, try to please each other in a new way each and every day.