The easy fix is to change the SS tax structure, I believe right now the tax is something like 12% of the first $87,000 of income, with no tax above that income level. I'd expect you would see something like a cut in the tax rate coupled with a lifting of cap. So perhaps you might see something like a 10% rate on the first $100k of income, or a smaller tax above the cap rate, say a 2% rate above $100k. You could make relatively minor changes such as this and extend the solvency of SS for another 20-30 years. You could also provider greater incentives against early retirement, or even shift the retirement age up one year.
I'm not saying I agree with this approach, but it is probably the most politically palpable. You might also see some economic benefit by reducing the tax on lower income people (perhaps also coupled with a cut in the corporate SS tax rate.