You could try sarcosine - usual recommendations are to use about 2g per day. Acts oppositely on NMDA receptors to dissos so theoretically maaaaaybe it could reduce tolerance.
Some people report using piracetam or other racetams which also have anti antidissociative receptor activity, although there is no evidence that either option will work, and not much in the way of anecdotal reports either.
I recently tried taking sarcosine for about a week for this exact purpose- but had to quit as it was making me depressed and also making me crave dissos even more. "Inner tension" is listed as a side effect - and understandably so - although it has also been trialled for depression. NMDA activity and it's role in regulating mood is complex to say the least.
AFAIK though there is no confirmed method to do what you are asking and I am sceptical of the usefulness of any of the options I mentioned. The best method is to simply take a very long break.
Using dissos for anxiety is also a dark and dangerous road in general IMO, and I would suggest looking for other options - even if those are other drugs.