A respawn is a feature that allows you to go back (X seconds/X.Xkmh) to allow time for the user to correct the train systems and save the user from losing the game from a single SPAD. This can stop from a frustratingly long route that you may be close to finishing but you are unable to due to a SPAD causing a service failure. Respawns can be earned by daily logins, special routes or purchased (10 respawns = £4.99)
Against any sort of micro transaction to cover this. TSW is not a tablet game. The feature should just be available as an option, maybe with the loss of 50% of the XP on that particular run.