Can Jam be reheated? I just got a bottle of strawberry jam. I am trying to make puff pastry filled with Jam and cream cheese inside it.  

I have never done this before. It is just an Idea in my mind so far. I need advice to know that can I heat the Jam in oven. The jam jar says to store in fridge after opening but nothing about it being heated. Can anyone explain whether it's safe to do so or not.
Sure it's safe, there's no risk in putting jam in baked goods. It says refrigerate after opening so it doesn't spoil after being left out too long - some people don't realize it needs to be refrigerated after opening because it is stored in the cupboard before opening. 

The important thing for food safety is to make sure that the pastries are eaten soon enough after baking. The cream cheese will go off sooner than the jam will, so don't let them sit around.