Should I adjust training plan when I slip up?

I'm currently at the end of week 4 of a 9-week RW programme to get me to 10km by March 13th. All has been going well so far, and all target distances achieved and target pace either achieved or exceeded.

Today's run didn't go so well. Target was 9km and I only made 6.2km; mainly due to overheating but also not helped by strong winds.

My question is this: next Sunday's long run was due to drop back for a week to 6km and then start ramping up again to 10km, 11km, 12km then race. As I only made 6 of the 9km today, should I count this as my 'recovery week' and try again for 9km next week, then 10, 11, 12, etc. Or should I still stick with the plan and go for 6km next week, and pretend today's lapse didn't happen?

I've only been running since last September, and this is the first time I've followed a set plan (other than Couch to 5k, which I did before Christmas). Not sure of the best way to keep on track.

Thanks for any advice.

 I would go for the 9 next week, otherwise you are trying to go from 6k up to 9k in one jump. Plans aren't written in stone, you won't come to any harm if you re-arrange the odd run.

I wouldn't worry either if next week you only do 7 or 8, just build gradually and you'll be fine.  If you can complete the plan and go into your race knowing you've run 11,12k or whatever, that's great, but you don't have to. Better to get to the start well prepared with a good base than exhausted/injured after slavishly following a plan.

That makes sense. I'll aim for the 9 next week but won't beat myself up if I don't make it: "No battle plan survives contact with the enemy.". Thanks for the advice.

I have had a similar day too - I'm training for my first ever half marathon (March) and first ever full Marathon (June). Last weekend I aimed for 6 miles and achieve 6.3miles non stop which is further than I've ever run in my life! I felt really good last weekend!
This weekend however not so good! Attempted 7 miles yesterday and only managed 2.5 as just felt exhausted. Decided to try again today. Managed 5 miles but included bits of walking as I could get my breathing to calm down. I know I'm exhausted from a stupidly busy work week but soooo frustrating!!
Should I attempt 7 miles next weekend or just move on to the 8 miles on my training plan?