I'd reduce my bolus doses (25% at a guess to start with, or reduce even more and see if you run high or not) throughout the day as the additional lantus will mean you need less insulin. You may well also run low between meals so have some snacks available. There's no harm in running a bit high for one (or two) day(s) while you sort it out, certainly easier and safer than running low all day.
Regarding moving it back to the right time, and the concerns of potentially running low overnight, I'd probably go for 50% of the lantus dose at the correct pre-bed time (and perhaps even have an uncovered bedtime snack, depending on how you feel your body has reacted to the additional insulin during today), and then accept running a bit high during tomorrow until the next evening lantus dose and it all settles back down.
We're all different though so there's not necessarily a correct answer.
Good luck, let us know how you get on!