Ipad Mini 1 crashes/reboots

I have my ipad mini 1 for 2 years now. It's been on ios7 since last year. About two or three weeks ago, the ipad started crashing a lot. It crashes with apps, it crashes alone, when I touch it, etc. Sometimes it crashes several times when trying to reboot by itself! It's impossible to use it like this.

I've done a Reset all settings, but it doesn't work... I wouldn't like to erase it because of the apps and everything in it... What can I do?