Illustrator crashes on my Ipad (7th generation)

Last few days this app was early slow, I couldn't move objects, couldn't export JPEG (it's continued to export blank file for a long, after 10th attempt the image was successfully exported). Today it can't open the file & crashes immediately as soon as I touch preview of my work. I'm so disappointed, my work has stopped for a day at least. I can not see any use in this laggy app anymore.