Sorry, I've just realised how badly phrased my previous post was.
Well, if you can store most of your preset messages in EEPROM that would be handy.
Maybe you can use 'Poke' to poke away a block of ASCII chars?
If you can common-ise some of the words/phrases then it can save space.
i.e. make up 'string' building-blocks in EEPROM.
In any event, you will have to read them back and plonk them to LCD one at a time in a loop as you know.
Tedious , but possible with a little patience and thought.
Think about how you can construct subroutines to do as much as possible.
You must remember that, whatever PIC language you use, a byte is a byte and a single ASCII char is a byte it has to be stored somewhere on the PIC. (Please don't mention compression).