Business Insider reports on the matter
The current set of restrictions was set to run through to 18 April and given the virus situation, this isn't so much a surprise. We'll see about the details later on and if Merkel will call for tighter measures such as nighttime curfews and such.
In any case, this will see the lockdown carry through to May at least. Just a reminder, Germany has been at least in 'partial' lockdown ever since November.