A proper Christmas requires planning. And doing a whole change in decorations requires extra planning, and time for purchasing....so absolutely perfect time to look!!
Have a look at Robeson Design on YouTube - she has a whole load of Christmas decorating videos, including trees of various sorts, and lots of tips and tricks. I think she has done a few more silvery/crystal type trees and other decorations over the years, and some which mix different ideas.
Don't throw things out if you have space to hold onto them, just get some new things for this year and trial new ways of doing things - but being able to go back next year, or to mix in the future.
Do you have anything already that would work with your ideas for new theme?
Are you planning on strictly white/crystal/silver or will you allow flecks of colour in there? (Again, this can help to use some existing decorations).
And don't just look at Christmas Tree decorations.
If you have any silver-y cookie cutters, thread a ribbon through them and use those as decorations.
If you have any little snowglobes, wire those onto a branch.
Pure white feathers that you get out on walks during the year.
If you can find some lovely pine cones and paint them white with some silver glitter over them. Or spray silver.
Look in charity shops for things that are lovely and sparkly (or would be with a good wash) that can be used on a tree.
You could bake "tree biscuits" and ice them in pure white icing with silver edible glitter or paint on silver lustre, or have "windowpane" versions using clear boiled sweets rather than coloured ones.
The pure white or the very pale blue Lindor chocolates that you find around Christmas could be hung using thread/ribbon.
Good luck, and enjoy the creative process thinking about it and finding things to put it in motion 
!!