i'm not saying i'm a freaking genius and i never spell anything wrong. i come close though. and i do understand the difference between YOUR and YOU'RE and how to use it in a sentence.
there is a replacement test that will tell you for certain which word will fit. read your sentence with "you are" in place of the "your/you're," intended. if it makes sense, then "you're" would be right. if not, then "your" would fit. you could also replace "your" with "my" in the sentence. if it fits, then use "your."
i just thought i should share this with you. for a better world.