Hi there,
In order to go Viral , you need a few things , have very good content that has the demand to be shared. Secondly , you need to push it in front of a large number of audience through paid sources or have strong assets like big groups / profiles / pages etc , where you share this and it would take off from there.
I am not sure what your existing strategy is , but for a youtube channel , the strategy should not be just going one video viral , but it should be to consistantly building your brand over time gradually growing so you are constantly in touch with your audience as well , and not losing subscribers / attention of your existing susbscribers.
The strategy will depend on the budget you'll have , go for longterm instead of shortterm gains.
Lets discuss this more over chat.
Thanks,
~ Syed