You can't update the unit yourself to a new card but if you have bought a second hand car which was already paired with a card you can put the contents for that card onto any VAG SD card whether MIB1 or MIB2, you can't move beyond the release that the car is activated against yourself. Saying this there may be procedures which you may find on the internet that might do it, or it may brick your unit. As mentioned there is a retrofitters process that opens those units up physically and then they mod the software on the unit. It could be that the FEC process that they use on MIB2 units has been mastered for MIB1. A quick check appears to be the case. It's a question of finding a local retrofitter to do the work to modify the navigation FeC (I believe). Trying to do this process yourself could brick the unit. Depends what your IT skills are. That obvious changes the opening paragraph.
That's the Google if you want to look further:
It's the navigation FEC of a MIB1 standard unit that needs to be modified. Generally this isn't required for MIB2 standard since there is a workaround so it's not something that's done. For the Mib 1 / 2 in high format it is done.