Single Page Application and short term token

[Stuey]

Hi . we have a issue with a Canvas app that has been build to update data in serveral sharepoint sites etc . however if they stay on a page filling in the information for to long the token expires and the user loses all work . we need to find a way of re authing without losing the work .  or if there are other connection options.  also cant seem to find what the time this short token last for 

thanks again