DPF regen

[passatawx]

Hi everyone. My Passat B7 2.0 tdi has started doing a regen every 80-100 miles. There’s no dpf or engine light on, only blue smoke coming out of the exhaust and higher revs for about 5-7 miles. I have scanned the car with VCDS and glow plugs 1.3.4 come up as faulty. I have also noticed that just before the regen happens, the coolant temp drops briefly by approximately 5 degrees C. The car has just under 130 k. On VCDS the Oil ash mass is 101g, oil ash volume is 0.25 L. I will change the glow plugs, but does my thermostat need changing too? Also, is the DPF still ok?(no DPF light comes on during or before regen). Cheers for any advice.