"refurbish" is good for your context.  If it just needed some paint, then "redecorate" would be good.  More commonly, people say "I am going to do up my flat". 

"refresh" is not used in this situation but we would probably guess you meant "redecorate" if there was no further context.

In American English: 

You 'refurbish' something that is old and worn, but still usable.

Example: I am going to refurbish my old bike. 

Repair is for something that is broken and cannot be used.

Example: I can't drive my car, I must repair it first.

Redecorate is only used to describe a room or house that you are changing. (This can include to refurbish it. However, refurbish implies that it was old or 'worn out', or an antique.

Example: I changed the color of the walls to redecorate my room. The paint was peeling and it needed to be refurbished.

Bonus: You can use the informal "fix up / fix it up" to mean both repair or refurbish. 

Example: My bike is broken, I'm going to fix it up tomorrow. Then, I will fix up my old garage, too.

Example: I'm fixing up my dad's old car.