To amplify on @Abeiku’s comments, inventory kits are only useful for “bundling” existing inventory items that are sold together. They cannot be used for production.
Manager does not currently have a capability for recurring production orders or bills of material. The best thing is to clone a previous production order. When doing that, you can edit quantities for both finished items and bill of materials. This at least ensures you don’t leave anything out. If you manufacture standard-sized batches, you might purposely create several production orders for varying quantities initially. Then clone the one that matches the batch you need to produce.
Of course, the ideal solution would be to call up a production order, enter the number of finished items, and have the bill of materials auto-calculate quantities. But the program isn’t there yet.