update probleme

Hello!
I have an ENFOLD theme since September 2014 for my music school (www.ecoledemusiquejocelynelaberge.com) and I have never encountered any problem until recently. I currently have version 4.0.5 and it’s impossible for me to update without losing my entire site. During the last two attempts to update I lost my site and I had to use the R1soft backup procedure.

My theme dates from 2014, so it is an old infrastructure and in the last two updates most of the errors observed seemed to come from the theme itself.

I am not an expert but I like to work with the ENFOLD theme. Is it possible to make an update whithout problems?. Do I have to buy a new ENFOLD theme? What do you suggess me?
Thank you,
Gaétan Gosselin