Windows Server 2008 / 2008 R2 and SQL Server 2008 / 2008 R2 end of support dates are coming in huge steps, so you really should be thinking of how to migrate these to newer versions.
If migration for these Windows and SQL Server versions is not possible and will not be in near future, there is a way to extend the support and it is called Premium Assurance. Yes, you have to pay for this, but at least you will stay supported and get security updates. And you can do this for six more years.
Anyway, I do recommend to save this as a very last option.
More info here https://cloudblogs.microsoft.com/hybridcloud/2016/12/08/introducing-windows-server-premium-assurance-and-sql-server-premium-assurance/