Hello startingrecovery,
I can only talk from my own experience but I fully understand what you're saying. The feeling of being clean can make us forget how strong the yetzer horah can be and we can become complacent. This happens no matter how many times we've fell for it in the past. I started to focus on this area about 15 months ago and at the start I could not get past 3 days. After a few attempts I got to 5 days and was very pleased by that progress. Eventually after some huge struggles I got to 2 weeks, and slowly I've been able, with Hashem's help, to improve and stay clean for longer periods. The level of 'cleanliness' during those periods has also become better, b''H.
What I'm saying is that I understand and have been there. Progress can be slow sometimes but as long as you don't give up, you will improve. Remember that some days are easy and some are hard, but it's in the hard ones that you find progress. Every time you are faced with this challenge and you struggle and succeed, you are becoming stronger in this area. As you become stronger you will find yourself wining more of the battles, getting stronger each time. Don't be disheartened by the occasional failure, look at your successes and your improvement. It's about progress not perfection.
Next time you're confronted with this yetzer hora, just remember that it's in these situations that progress is made, and it's davka when it's so very difficult that Hashem is cheering on the most. Avoiding the aveiroh when it's really difficult is what gives Hashem unimaginable nachas, and puts you in the category of mekadesh shem shomayim baseser, along with Yosef Hatzaddik.
As for a practical method, I can tell you what I've been doing, but you have to decide for yourself if you're ready for that. I have made a taphsic neder. This is what I wrote elsewhere:
The last time I 'binged' I felt very depressed and I called GYE for support. The tzaddik who I spoke to introduced me to the taphsic method. I thought I knew about it and was doing it but he told me a better way to do it. Here's how it works: You make 2 knasos, one big one small, for example $1 to tzedaka and $100 to tzedaka. Then you make a 'get out clause' or tnai, this is something that you will do before falling, for example say a perek tehillim, go for a walk, do push-ups etc. These are things that make you pause and give you time to think.
OK, so you have your 2 knasos and the t'nai, so you make a promise to Hashem that the next time you fall you will do the big knas, UNLESS you first do the t'nai, in which case you'll do the small knas.
For example, you get the urge to look at porn so you head for your computer. Then you remember that you'll lose $100 (big knas) if you look right now, much easier on you if you first walk around the block (t'nai) and then if you look you'll only give $1 (small knas).
This is the way I understand it, see here for more details:
guardyoureyes.com/the-gye-program/20-tools/item/tool-10?category_id=278
The point is that this is a habit. A habit is when the impulse to do something is followed immediately by the action without any thought. To break a habit you must start by slowing down this pattern and giving yourself time to think it through. Even if you then fall, at least you're starting to break the 'autopilot' and gain control over yourself. Every time you do it you become stronger and further separate the impulse from the action until they are not connected at all. Then it becomes much easier to control the urges.
I hope this helps. Just remember, we are human, we are not perfect, and if we can still try our best to serve Hashem, that is what Hashem truly cherishes. Hashem truly cherishes you.