If its a long quote i find it best to break it up into smaller phrases and repeat the small phrases over and over again till you get it. The put all the phrases together and seem if you can remember the quote. Also writing them out over and over again helps x
write them again and again if u can relate them to the context they are in the play so when u think of that u can at least remember a bit. what i do is record myself ( if you dont like the sound or your voice do soeone else) and listen to it