Although we have yet to start the minibot, I've been thinking about using a layout like this to control the motors. I quickly sketched it up to share:
S1 is the "pole" switch, which is activated while the minibot is touching the pole.
S2 is a switch that is activated at the top of the run. It disconnects power & shunts the motors together, slowing them down.
S2 is tricky, though. It needs to be a SPDT toggle switch, not just momentary. Also, it needs to be "break before make" style, otherwise you'd short the battery & blow the fuse.