The 1AR restart is a strategy where the affirmative chooses not to extend any of their 1AC into the 1AR, instead deriving entirely new offense by uplayering in the 1AR, which effectively "restarts" the debate in the 1AR.
The 1AR restart can be strategic when the negative much further ahead on substance after the 1NC. Since the affirmative is reading entirely new layers and offense in the 1AR, the negative's only chance to respond will be in the 2NR, which invalidates all of the negative's time spent on substance in the 1NC. A full 1AR restart should probably only be used as a last resort if the affirmative thinks it will be extremely difficult to win on their arguments as of the 1AC.
The 1AR restart should contain a variety of different layers and strategies to give the 2AR multiple options. It might seem tempting to just read many theory shells, but that could be incredibly unstrategic since the 2NR could invest all of their time answering paradigm issues, making the 2AR near-impossible.
An ideal 1AR restart should contain both theoretical and substantive outs.
Theoretical outs can take the form of theory shells extended from the 1AC or new 1AR theory shells. These theory shells should be as unique as possible to prevent the 2NR from grouping them together and answering efficiently. If the negative has read theory in the 1NC, you should invest a good amount of time weighing your 1AR theory shells against the 1NC theory shells to make it difficult for the 2NR to collapse to them.
Substantive outs typically take the form of permissibility triggers, skepticism triggers, presumption triggers, or hijacks. It is essential to have a potential out on substance in case the 2NR sufficiently answers your theory arguments. This means that you should write your aff with the tools to allow for a 1AR restart if necessary by including arguments that could be used to trigger permissibility, skepticism, or presumption, as necessary. If, for example, your opponent concedes that permissibility affirms in the 1NC, a 1AR restart might be an especially viable strategy.
Finally, some debaters may read additional independent voters such as reparation Ks to provide additional routes to the ballot.
This 1AR restart contains a combination of theory shells, hijacks, and permissibility triggers.