Hello & Welcome,
Can you send along the first two characters of the Serial Number of your unit?
If they are the right letters, then there may be an upgrade SD (memory) card that you can purchase for your unit (Nextar does not offer these for free).
It looks like that particular unit can use the SD card upgrade.
If you go to the following page, you can get all the details about purchasing this memory card:
Click Here to see about purchasing a map upgrade SD card.
I would also check out the FAQ page for this unit and make sure that they have these available and that you are actually upgrading before you make the purchase.
Click Here for the FAQ page.
They even have a toll free number that you can all at the bottom of that page.
I hope this helps. Please let me know how this works out for you.
Take Care, Greg A.