Looking on the internet deeply has found these results:

If you do it again I will kill you is the most popular phrase on the web.

If you did it again I would kill you 10 results on the web	If you do it again I will kill you 13 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
It doesn't look like this phrase is very popular! The search could not find any examples on the internet.	"You struck me on the head while I slept," said the giant, "and if you do it again I will kill you." Then they went to sleep again. When the boy heard them snoring ... I hate you you made me have the suckiest team in the world so if you do it again I will kill you I won't be here I will find where you live and I will kill you. Jul 21, 2011 ... “I told you I would tell him, by Sah if you do it again I will kill you in your sleep and dissolve the union, Halum.” By her look she meant it too.

If you did it again I would kill you

10 results on the web

If you do it again I will kill you

13 results on the web

More popular!

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

"You struck me on the head while I slept," said the giant, "and if you do it again I will kill you." Then they went to sleep again. When the boy heard them snoring ...
I hate you you made me have the suckiest team in the world so if you do it again I will kill you I won't be here I will find where you live and I will kill you.
Jul 21, 2011 ... “I told you I would tell him, by Sah if you do it again I will kill you in your sleep and dissolve the union, Halum.” By her look she meant it too.