In a perfect world, we'd all be able to get affordable mortgages at rock-bottom interest rates when buying a home. But we don't live in a perfect world, and sometimes the only mortgage you can get is a pricey one. Fortunately, you're not stuck with it for the next 30 years: You always have the option to refinance.Here are a few situations where you may want to consider it.Mortgage rates are currently at a seven-year high and hover around 4.6%, but they're still very low, historically speaking.