For keeping the initial Grid state I would suggest an approach that is very similar to the one used for persisting the current state.
The default state should be persisted separately from the current state. If you are using localStorage I would suggest using a different key for the initial state. The entries in localStorage would look similar to this:
In the document.ready() event check if there is something present in localStorage["default-grid-state"]. If the entry is null that would mean the Grid is loaded for the first time and you can save the settings there. Reloading the page should not save the settings again.
As for keeping the current state you can use the approach you already have in place.
Give the suggestion a try and let me know how it works for you.