To sell or not to sell that is the question

Hello All,
Hope you all enjoy a great Christmas!  I have a property in Blackwater and have had this for 2 years.  It has good rent and is cash flow positive and is paying for itself.  Though it is not costing me anything, I don't know whether it will make me any money in the short to medium term.  In other words if I sell it I could perhaps buy something that would improve capitally (though I might have to sink money in to prop it up) in the future.  What are your thoughts?  Anyone know more about Blackwater?  I have not been there and don't know what works if any are proposed.  My rental agent says rents will go up again soon.  I am undecided and not knowledgeable enough about what would be best.

Cheers,
Tina