Hello yngsTR
You cannot initiate the picture exchange process yourself if the photo is, according to the policy, not yet outdated.
If you want a new picture, you have to go to a station ticket office. The staff there can initiate an extraordinary photo exchange. Be informed that a new SwissPass card will cost you CHF 30 if it was not necessary to change the picture from the SBB perspective but it was your personal wish.
Kind regards,
Roland