1. Inflation. Refinancing debt with a lower rate is always a favored solution under high inflation circumstances.
2. Family income. Growing family income is pro refinancing because ones can pay down the principle in an accelerated pace with extra money each paycheck.
3. Tax rate. Marginal tax rate ones are subject to shall be taken into consideration too. However, it is a factor out of an average people's control.
Don't make case too complicated due to these uncertainties. Refinance as long as you feel comfortable to do so.