Sort by price

Sorry this is totally my own fault….to get the plugin looking and behaving exactly as a client requested I previously altered the actual plugin files (i know I should have created a child theme etc but certain files just didn’t seem to want to play ball) I knew it would come back to haunt me as one feature they really wanted was sort by price which I see is now available. That would be great but as I altered so much I’m scared to update the plugin.
So the short question is….which files would I need to edit and what would I need to add to enable the sort by price
Apologies again and thanks for any help anyone can give

https://www.ads-software.com/plugins/easy-property-listings/