An end of a relationship does not signify an end of feelings that you could have for your ex and vice-versa.
Your ex could be cursing the day he/she ended ties with you and could still care a lot about you.
He/she could indicate this feeling in many ways and you would need to simply interpret the signs to be sure.
Your ex asks you to at least remain as 'friends'.
This move indicates that your ex wants to keep communication lines open between the two of you.
Your ex could also be hoping that he/she could easily convert friendship into love should the need arise again.
Your ex would also try to remain in constant touch with you even if it was only as 'friends'.
Your ex keeps tabs on you.
Your ex could keep tabs on you including your daily activities and especially your 'dates'.
This would be done through mutual friends as your ex could ask them for daily updates.
This indicates that your ex still cares for you and is also threatened by any rival 'dates' that might try to enter into your life.
Your ex's body language displays true feelings.
Your ex could display feelings of renewed love whenever he/she stands besides you.
Your ex could suddenly turn shy, lean closer or even start fidgeting with his/her hair while talking to you or standing next to you.
This could truly indicate that your ex has lost all anger from his/her body and that it has been replaced by feelings of love.
Any excuse is valid enough for your ex.
Your ex could exploit any minuscule excuse to call you up, email you or rush over to meet you.
Your ex could also try to chat up with you longer every time he/she 'bumps' into you or calls you up.
You might also notice that your ex tries desperately to see you or at least talk to you once in a day.
This could indicate that your ex is missing you terribly and has desperately started caring for you again.