How to save in Ms outlook without having trouble in end date?

I have been using Microsoft Outlook 2007 for quite a while and this is my situation.
I have a recurring appointment set but it doesn’t have an end date. I have edited single occurrences of this appointment in the past. Now, I would like to set and end date but whenever I try, I get a prompt message saying that I will lose any exceptions to the series.
Is there anything I can do to save the exceptions but still be able to remove the recurrence from this date onwards?
I hope you can help me with my situation. Thank you.
