I'm afraid I've built up a tolerance to my Zoloft, how long should I take a break from it to get it to work?

I'm taking it as an anti-depressant, it used to help, but now I notice no difference if I take it or not. I cut my dose in haft so I'm only taking 50mg now. I'm gonna totally stop taking it for a few months. Then go back to 100mg (what I was taking) or maybe something higher. How long do I need to stay off of it for the tolerance to go away? Thank you.