Vasectomy reversals are possible but they are expensive and are carried out in specialized centres under microscopy. A vasectomy cannot always be reversed successfully and while the procedure may be a technical success, the immune system may have produced antibodies in the period of time since the vasectomy which interferes with healthy sperm production. In general terms, the greater the time interval between the original vasectomy and reversal, the less likely it is to have a successful outcome.
Most fertility experts now recommend gamete-harvesting from a testicular biopsy and transfer to an egg to optimize the chance of a successful pregnancy.
While storage of sperm in a fertility centre is possible indefinitely, if you are unsure of your long term plans, it is better to delay vasectomy until you have given the decision more time.