Tomorrow will b, I'll take my last exam at themy university.

You could also say "Tomorrow is my last exam of university"

Some classmates advised me thato speak loud and clear.

I'll try to do itso, but csometimes I have a nervous laugh in thisese situations.

Before the exam, I have a class in the laboratory.

In university, we sometimes call these classes 'labs'. Ex) Before the exam, I have a lab. --> This is not really a general term, but in my university, we say it often.

I wish I didn't fall asleep while studying.

It's an important exam in the year, I feel so nervous.

I have some thoughts about this line, but I'm unclear of the exact meaning you intend. "in the year" is awkward phrasing on its own because it's not clear what the difference between it being important, in absolute terms, or only within this year is. Is it more important than other exams? Does it count for a higher portion of your grade?

"I'm so nervous; it's the most important exam of the year!" is kind of the line I'd expect here.
"It's a very important exam so I'm feeling anxious about it." is maybe better if you don't want to claim it's the MOST important, but you can't afford to fail.

Some classmates advised me thato speak loud and clear.

I could be wrong on the technical specifics, but here's how I think of this:

"...advised that I should speak loud and clear" would also be fine. When you say "that", you're essentially starting a new independent clause describing the advice and so there's a need to reestablish the subject, which is now yourself, "I".

"to" is a bit simpler here because "advised me to" keeps you as the subject.

I'll try to do it, but csometimes I have a nervous laugh in thissuch situations.

this -> The situation you're in right now
such -> The type of situation being discussed

I wish I didn't fall asleep studying.

"Didn't" feels a bit off here, but it's not entirely wrong, I think. Still, if you mean you habitually fall asleep while studying, I think "wouldn't" would be more clear, and if you mean instead that you hadn't fallen sleep studying, "hadn't".