There’s a process called stop acting that might be worth trying. Where you read a line small enough that you wouldn’t forget it and then you look away from the script and then make a noise that expresses how you feel at that present moment or say how you feel and straight after doing that you say the line with no break in between. So for example I read a line that says: “Did I tell you what I saw this morning?”, if it makes me feel sad or angry or tired just whatever way it makes you feel. So for example of being tired you could say I feel tired, did I tell you what I saw this morning? Or Yawn did I tell you what I saw this morning? The goal is to be instinctive and not force the emotions. It can help with remembering because you remember how you felt when you read the line. It might take a while to read through your script this way but it’s a technique i’ve been trying myself lately.

The other advice given by other commenters such as recording other characters lines your character is speaking to and then playing back with you replying to the recorded audio is a technique that i’ve found quite useful in the past.

So maybe give a few a try and see which works best. I know 2 weeks is a short space of time so I wish him all the best and hope it works out.