GERMANY D2 pre-Paid How long is Sim valid ?

Hi

I have a D2 Sim from Germany that I have used for the last 5 years ,
But I did not go to Germany last year so its been 14 months since its been used.

How long is it Valid for ?

If its still good (how would I check ? ) is there a way to put money in it over the web ?

Thanks for your help

RB