Yes, I did mine the year after we bought this house. I was successful. Two takeaways from my experience:
1)Make sure your "ask" is reasonable and is based on hard numbers.
2)Gather comps from your neighborhood (same street/block if possible in at least one example) and base your value on SF as much as possible. I'm guessing your addition is part of the jump. State law says they can only go up by a maximum percentage (10% in 3 years, iirc), but your addition might have triggered a new valuation.