The technique described below may work in a similar way on other Garmin models and on other sat navs and navigation devices but they have not been tested.
The answer is probably neither.
There is probably a quicker way back to your intended route than following back the way you have just come. If nothing else, retracing your steps is demoralising. But you shouldn’t use the recalculate route option either.
So how can you navigate back to the route without losing the original navigation on your route?
Flick through the screens on your Garmin until you locate the map screen. Zoom the view out by clicking on the ‘-’ symbol until you can see your route. By eye locate a point on your route where you could re-join it. Then zoom in on the point using the ‘+’. You will probably have to move around on the map if you are some distance from your route. To do this click on the ‘arrows’ symbol and then drag your finger around the screen to move the map.
Once you have located the point where you would like to re-join the route and zoomed in to get sufficient detail, press that point on the screen with your finger. A large pin should appear. You can drag it around if it is not quite in the right place.
Now press the location name box or the symbol with three lines at the top of the screen. A new screen will appear giving a grid reference for the point and the distance to it (in a straight line). Click on the Go button at the bottom of the screen.
The sat nav will now navigate you to the selected point. Once you reach that point and re-join your original route the sat nav should then automatically continue navigating along that route.
You can also use this technique to navigate around impassable obstructions, such as closed roads (although few are closed enough to stop a determined cyclist) or obstructed paths. You may have to do a two part operation though, one to take you away from the obstruction and another to get you back to the route, otherwise the sat nav will probably just route you through the obstruction again, after all, it doesn’t know it is there!