How can I best appeal my property’s assessed value by the county?

[Yael Maroko]

Following a major rehab I did for a rental, I got a new property assessed value from the county which is double from last year's and is even higher than what I got from the appraisal done on the property when I did a refi (by about 15K, not that much) 

What's the best way to approach this? Do I send them the appraisal I have and ask to reduce? 

Any other strategies?

Thanks