I had two ablations for avnrt. I still have no tolerance for activity and experience shortness of breath. What can I do?

Avnrt. Sounds like you need detailed evaluation to find out why you have these symptoms, consult your doc please.
Avnrt. If your symptoms correlate with recurrence of the arrhythmia then you may need medications to help. If no arrhythmia can be documented then other causes need to be considered.
Is the AVNRT gone? Sometimes heart rhythm monitors ("holter monitor") can help detect recurrent arrhythmias and correlate with symptom episodes. Avnrt, if successfully ablated without complications, should not have any permanent effects on heart structure or function. Generally an echocardiogram (cardiac ultrasound) is done at the time of initial diagnosis, which would have ruled out underyling abnormalities.