there's been years where i've straight up regressed, and yea... it sucks. i'm talking going from switch 9's and corked spins to switch 3's and 540's over a one year period.
generally, what i find helps to get your shit back is having confidence in yourself and commit to your goals. it's a weird thing though, you know? most of the time there's no one there to tell you what you should and shouldn't try, so it is easy to get into a slump of just doing what is most comfortable and never get out of that zone... I think if you put enough energy into it, and truly love what you are doing, stuff will happen.
About two or three years ago I told myself I wouldn't allow myself to regress anymore. My mentality is, I love skiing more than anything else I do in life, and one of my biggest fears is getting bored and loosing the love. To make sure this never happens, I try to accomplish something significant every time I put skis on my feet. If I'm constantly improving my skiing, it should always have that fun and excitement that I love about it, and therefor, I will never grow tired of it and quit. That is my motivation to keep pushing it. You just gotta find yours.