Is it good time to refinace my home loan?

I just purchased a house last summer. I have 2 loans on it; 80% at 6.2% & 15% at 7.8%. Is it worth to refinance and pay additional closing cost? Will I have to do the appraisal again on my house? What happens if the home price has appraised down? What happens if the home price has appraised up?