1. Create new project file using your std. templates (if you have).
2. If needed import line types (maybe also another attributes) from other sources (.pln, .pla, .aat).
3. Create a back-up copy of LineTypes in *.aat format.
4. After sorting also save a list of new line types in *.aat format.
5. Save file as new .tpl, if you have used your std. templates.
Note: I recommend you to use these changes in new projects, because of possible "conflicts" with some library parts. Most used LineTypes & Fills by std library parts are: "Solid line, Dashed line"+"Solid Fill, Empty Fill, Air Space, Minimal Space".
Be careful with some add-ons created LineTypes/Fills (for example ArchiStair creates LineType AStair_dashed)