With rare exceptions, a leaking WH means it's time to replace. Sometimes, you have a little time, but there's no guarantee it won't quickly be a flood rather than a trickle.
A 12 year old water heater is a senior citizen. Some last longer, some much longer, but when they do they are the exceptions. Assuming the leak is from the tank and not a pipe to or from the tank, a new heater is in your immediate future. Now tank repairs are possible.