Not a thing except, perhaps, educate the people sending you texts. SMS, the protocol used for texting, is limited to 140 octets or, in our alphabet, 160 7-bit (the non-pseudo-graphic) characters. That's the way the system was designed and, for many technical reasons, it's going to stay that way. They can use apps that take all the text over 160 characters, form it into a text file and attach that file for you to download, or - if they really have to say more than 160 words [I'm one of them - why use one word when 5 will do?] use email, which - practically, at least - isn't limited if it's strictly text. (How many people can stand to type even 10 million characters, and that would be a pretty stingy email service these days.)
But I don't know of any SMS apps that will take broken RECEIVED texts and figure out how to paste them back together again. (There's no indication in the SMS where it broke just because it hit the 160 mark, or where it broke because your sender broke at a 160 mark, then sent you a separate message.)
