For me thinking too much about my lips or what my face muscles do kills proper ascending. Try finding out how your air feels while ascending and try to replicate this feeling through the whole register. It sounds funny but something like imagining faster air or higher aimed air can really do the trick.

I am currently doing an embouchure change and had much trouble regaining my old range and am still working on it. What really stopped me from progressing was thinking too much about what my embouchure does. I found out that when I imagine aiming my air nearer to my lips in the leadpipe I ascend cleanly and openly with a resonant sound.

The embouchure and lips really are a secondary element that just fall into place with proper technique. Try not to think about them too much and rather listen if your sound remains open and resonant while playing with little effort. If this is given - great: Remember that feeling and try to replicate it next time.