There are many reasons we may feel we need to re-connect with our horse. It may be that you've been away for a while, or things haven't been going so well and you've given up for a while, or you just want to strengthen your relationship with your horse etc...

There are a few very effective ways of doing this but all carry the same principles
Forget your agenda or training regime.
Allow the horse it's own relaxing time with you without having to be obedient and regimented.

You can very well set clear boundaries with obedience during training, riding or working times and you can also set more relaxed boundaries in other times where you just want your horse to relax. You can let your horse know you would like it to switch to more obedient work time, by simply saying to the horse "work time" and it will come to know a certain amount of concentration is expected during this time, and the same when you want him to relax you can say another cue, such as "all done" or something else clearly remembered like "relax time".

Where alot of people make their horse frustrated and very sour, is requiring high concentration and obedience for more than an hour.
It is common knowledge a horse has a concentration span of only an hour. If you decide to require longer from him training and behaviour in general will no doubt regress from that point.

Always leave your training, riding, handling etc... on a positive high note, never a bad one. Your horse will remember and start from where you left off. If you've had a futile and bad ride or day with your horse, which can happen so often don't worry, we're all only human...and horse, but we're trying!!... pick yourself an overly easy task you know you will 'win' with, such as some easy ground work task, when achieved, say good boy and leave it on that high note, your horse will remember you are still onto it and all is positive.

Always be aware if the horse is becoming uncomfortable, sweaty, ticklish with sweat under the saddle and tired from carrying your weight and hop off and give him a break without the saddle if you can.
If training in groundwork, little breaks and a pick of grass often help too.
With all that addressed and sorted while you are in serious work mode, you have a good start.

However if you really want to freshen your horse up and re-connect, it's a good idea to forget everything and just spend some time with them with no agenda in their own paddock or taking them out for a walk where they want to go to eat grass or explore, socialise etc.
This does wonders for a horses demeanor and yours when you see how refreshed and happy they are and you get to spend that happy time together.
I suggest including this as part of your more serious endeavours and at least once a week if you are working daily.

Another good idea is treats and time out with a good shampoo and relaxing pick afterwards etc...
The key thing is: This is relaxed time not work time. Let your horse be like a pet dog, and explore etc, you will be amazed at what this does for their confidence and mental attitude.

Watch your horses eyes always, they are very telling. If they are black you are in trouble. This is an angry or scared horse.
If they are milkier normal brown they are relaxed but not really happy. If they are milky with a pale blue ring around them your horse is very happy and relaxed.

Here's a test for you... Go into your horses paddock and up to your horse, look at the eyes, see what colour they are then start to gently pat and soothe the horse and watch the eyes, the blue ring will appear right before you while you're watching.

It's incredible how a pat and a kind gentle word go such a long way ;)