Are there some acceptable cases that clonazepam can be taken for a lifetime for the management of chronic panic disorder? thank you?

With every medication, there are pros & cons. There are unclear long term risks from chronic clonazepam use, but in someone with severe panic disorder, those risks may be outweighed by improvement in daily functioning. Either way, other lower risk treatments should be maximized (i.e. SSRIs, CBT) to offset the reliance on benzodiazepines. Please discuss more with your psychiatrist.