Im in the underdark right now and i just wanted to know if i can go after the red or shadow dragon again now that i wont die on the spot now or did i mis my chance?

Killer Dwarf
The Baby Killing Paladin

YES.
And I would advise you to do so because of the items.

They won't be as hard, but you'll still have to use some tactics...

Do a search on the subject if you're looking for strategies, SP has an unhealthy number of posts about them :).

Great Thankz for the Help

You can still do anything (I think...) that you could have done in chapters 2 and 3 in chapter 6.