The short answer is it depends on the precise language of your order regarding alimony.
Typically, an order that has a definite termination date of alimony cannot be modified after the termination date. Also, depending on the date of the order, your ex-wife could be past the deadline for appeal. If you are at the point where a five-year agreement ends, you are obviously out of the appeal time frame.
On the other hand, sometimes alimony orders are modifiable if there is a significant change in circumstances or in rare cases, the order can be opened up by the court if there is any fraud involved in procuring the agreement or if your ex-wife comes to find out any new information that was not disclosed to her upon entry of the order, etc. If such circumstances exist, your ex-wife may be able to reopen the issue.
Finally, it may depend on the circumstances surrounding the alimony order. If your ex-wife’s alimony terminated when it did because she had the ability to support herself, that should prevent a modification.
I cannot give you specific legal advice as I am not familiar with the facts of your case. For a more in-depth answer, please consult a family law attorney in your jurisdiction.