Preserving row total calculation done using jQuery across postbacks in asp.net

hi

 i want to finish this task as soon as possible but i am struggling.

i used jquery calculation with onchange then dynamically added new row,

calculation is working good but when i click addnew row button,  total value is cleared.

how to persist the value after i button clicked

below are my sceen shot

before click add new row button

after i clicked addnewrow button the amount values are cleared