There could be a number of reasons why your levels are high. If you are unwell or stressed, this will raise your levels. However, if you feel ok (apart from the high blood sugar), I would be tempted to change my insulin pen or cartridge. As your levels are constantly riding, your basal may be more likely to be the culprit. However, when our levels get to double numbers, we experience insulin resistance. I need twice as much insulin to lower a high above 15.
When I am unwell, I increase my basal. However, the long flat profile of Tresiba means a change can take 3 of 4 days to take affect so it is not easy to adjust.
I would also recommend keeping a close eye on your ketones.