Primary Home 2 Year Tax Exemption Question

[Kate Struzenberg]

I have been living in my primary for over 20 years.  I have a 500K paid for primary home.  If I sell and buy a new home for around 500K again, live for 2 years and it goes up in value to 750K.  I sell again, what is my tax exemption scenario?  Can I exempt the 250K profit?(750K-500K)  I know it is 250K each person, 500 couple. And then buy a place for 750K and live 2 years and it goes up to 850K ( write off 100K) and so forth.

Thanks, K