How to bring the spark back in a relationship?

I (18f) and my boyfriend (18M) have been together since we was 15. Lately, I feel like the spark has died and we have just grown comfortable with each other. The relationship has stopped fulfilling me emotionally but it hasn’t him. He’s my best friend and I love him to bits and don’t want to hurt him. We’ve had a talk and I have had a think that we are going to go on a break and then try to rekindle what we once had. The break may be hard as we both have the same friends and go to the same college which is why we are wanting to try to rekindle as if we break up a lot of things would have to change.

The spark has also left sexually. Both of us find sex boring. Not because we find each other uninteresting but because it feels like a chore rather than something we feel. Before anyone comments about breaking up I am not interested as that is our last option. Any tips?

**TL;DR;** : we want to bring the spark back romantically and sexually. Any tips?