Need tips for speech block with upcoming presentation.

Need tips for speech block with upcoming presentation. I have had a speech block for a while now. Its not too serious, most of the times in normal conversation it doesn't affect anything. However, sometimes, especially in high tense situations when everybody's attention is on me, I freeze up in speech. Its not a stutter where I repeat sounds, the words just don't come out and I usually end up repeating phrases. I have a presentation for a class in a few days. Its the third one this year. For the last two, I've been able to get by through heavy practice and recital. Whereas most students would just improvise on the spot, I prepare lines which I would recite word for word. Usually that works out pretty well. However for this presentation, I might not be able to do that as we haven't worked out whose presenting what. In the case which I can't recite, it would be very helpful for some general tips on how to reduce speech blocks and any practice drills.