Mark,

You do not have to be dispensed from private vows you have made. If you have made private vows which are contrary to the Church, just bring them to Confession.

The only time you would have to be dispensed by a bishop for vows you have made is if you were a Catholic religious, whether a sister, monk, or priest.

Yes, some vows are forever. Priests, Sisters, and monk make solemn, life-long vows.

I hope this helps,

Mike