The only real solution is to raise the pension age, despite how unpopular it is, and make affordable to have kids.
The raise in the age is obvious: as long as the life expectancy increase you have an increasing part of the population to pay. It is cynical but there is no way that a system designed to handle a 75 years life expectancy could handle a situation where a 85 years life expectancy is the norm and not the exception. Moreover, probably a 60 years old today is more able to work than a 60 years old in the 1980's. (the ages are just an example, but you get the point).
And the only obvious way to compensate for more old people is to have more kids (the other is to increase immigration, but you should only allow people who do not burden welfare).