It might be worth upping the dose if Cipralex works for you and has a history of working for you. However, the literature suggests that after 20mg, there are diminishing returns (meaning that if you don't respond to 20mg, increasing may not be effective). Additionally, if you've been on the same medication for a number of years, its not unusual for it to stop working. Your body simply acclimates to the drug and over time it loses it's effectiveness. In that case, changing medications could be beneficial. Switching to another SSRI like Prozac or Paxil may be worth looking into as their chemical structure is slightly different from Cipralex (also known as Lexapro). Your body won't recognize it and should respond.
The good news about that is that after the switch, if you feel like going back to Cipralex in a year or so, your body may respond again. It just needs sufficient time to get out of your system.
My best guess is that after 7 years on the same drug at the same dose, your body just got accustomed to it. Also, we change as we age. Hormones and other factors always play a part in our mental health, so it could just be a function of how your body is responding over time.
Finally, if you keep having feelings of depersonalization, be wary of other drugs like benzodiazepines (xanax, klonopin, etc) or sleep aids, as they increase dissociation. I would stay away from alcohol or marijuana as well.
I hope this helps - please let me know if you have any further questions!
Best of luck to you,