Better plans of new Positions

Usually, when you're playing a game, you make moves with a certain plan. When you've passed the opening phase, you'll have to make up a plan like "Starting a kingside attack with pawns/pieces" or "Preparing the c7-c5 pawn break". You then make up moves, according to this plan, and start executing the plan. Sometimes your plan was good enough, you get to achieve the purpose of your plan, and you continue to a new phase of the game where you make up a new plan. However, in some cases, your original plan seems to be insufficient. It turns out your opponent can easily stop your kingside attack, or white can prevent c7-c5 by controlling c5 with enough pawns or pieces. What to do then? Many people in this situation will still continue with their plan, hoping for things to turn out right anyway. They'll think "Maybe my opponent doesn't see he can stop the attack easily" and just continue the kingside attack anyway. Sometimes they get away with it (the opponent makes a mistake), but in other cases the opponent does play right, defends against the kingside attack while executing his own plan, and wins. Better however is to stop and take another good look at the position and your plan. Do I have any better plans than this plan I have now, which doesn't look so good anymore? Is it better to stop the kingside attack now, before it backfires on me? Sometimes you'll conclude it's still best to continue your previous plan, but in other cases you'll be happy to have realized in time that another plan is better now.