.
When you disconnect the battery the map sets back to Revo's 'stock', but when you use the switch to reload the 'Revo' remap, it will load the same Revo B/T/F settings you had previously. So no problem or visit to a Revo dealer necessary.
If however, your VW dealer flashes your ECU with an update it will effectively cancel your Revo remap so you would then need to have that reinstated. Some Revo agents charge a small fee for this and others don't. If they don't already know you, you may have to prove ownership of the Revo licence.