226 is fast. My avnrt was clocked at 230 and it felt crazy manic fast and I thought I would pass out. So I can understand your desire to want to get it corrected. Unfortunately there isn't much beyond ablation that would stop it for good but the type of svt you are having can predict the amount of success you might have with ablation. What type of tachycardia do you have? Afib or a reentry svt like avnrt? Usually the reentry svts like, avnrt, wpw, and avrt should be easily corrected with an ablation. Afib is a bit harder to correct as can issues near the sa node causing runs of pacs or PAT. It is possible you had a few spots that were causing a reentry pattern and could be why you are needing repeated ablations but I would consider finding a new EP considering you have had what appears to be 2 failed ablations. At least have them explain to you why it is not being corrected and what are the odds of creating a bigger problem with repeated ablations.
The medicine they give to try and control the tachycardia is dangerous in and of itself so if you can get good assurance that the next ablation will do the trick then it might be worth it but I think understanding exactly what you are trying to fix, where it is at, and what effects repeated ablations will have may be good to know. As well finding a new EP may be necessary, one with extensive experience and expertise in the type of svt you are having. Well best of luck with it all. I do hope you can get it resolved once and for all. Keep us posted on how you are doing.